Hidden World

“Hold it there.”

Mara knelt beside the sled and steadied the mast while Signe locked the last collar with mittens too thick for the work. The portable loop antenna rose in sections, black tubing silvered with rime, and wagged once in the wind before settling. Behind them the two snowmobiles idled on low choke, exhaust flattening sideways and vanishing into the white.

Elin had the receiver case open on the sled. The headphones lay around her neck; the lead trailed down into a nest of batteries wrapped in foam sleeves to keep them from dying too fast. She turned the tuning wheel a hair and listened without expression.

“Well?”

Elin lifted one gloved finger. Wait.

Mara kept one hand on the mast. Through the insulated layers she could feel the fine shudder the wind put into it. Nothing here kept still. Not canvas, not aluminum, not thought.

Signe leaned close to the compass housing mounted at the base. “If it’s shifted again, I’m blaming your wiring.”

“My wiring is the only reason we’re not listening to weather reports from Chile.”

The headphones came off Elin’s neck. “It’s there.”

Mara looked up. “Stronger?”

“Cleaner.”

That was worse.

Elin handed her one side of the headset and kept the other. The cold had stiffened the cord. Mara pressed the pad against her ear. At first she heard only the dry sea-noise of the band. Then, underneath, the repeating pattern emerged: three measured ticks, the wash of static, then the pulse that was almost speech and not quite.

Not loud. Near.

She rotated the loop by inches. The signal swelled, thinned, swelled again. At the peak it cut sharp enough to raise the hairs on the back of her neck under wool and fleece.

“There,” she said.

Signe noted the bearing in pencil on the Rite-in-the-Rain board strapped to her forearm. The pencil point snapped. She cursed softly, fished out another from the chest pocket of her parka, and wrote harder. “Same line as camp. Maybe two degrees north.”

Elin shut the case with her knee and stood. Frost had gathered in her eyelashes; when she blinked, it broke. “Good. Pack it.”

No one said they had only just left camp. No one said the visibility was already thinning into that flat, sour milk color that erased horizon and ground at once. The rule was four hours. The rule had come with conditions. The rule was moving, like everything else.

Mara collapsed the antenna and lashed it down. They had flagged a route from camp with orange bamboo wands every hundred meters, but three stops out the nearest marker was already a dim bruise in the white behind them. Ahead there was only the GPS unit clipped to the handlebar, the green line of yesterday’s rough plan, and the instrument sled dragging the radar array like a coffin lid over the snow.

They rode in staggered order, Elin first, Mara second with the receiver, Signe rearmost watching for drift and hidden sastrugi. The machines buzzed under them, skis slicing through powder crust, rear tracks throwing chalky tails. Every few minutes Mara lifted one hand from the throttle long enough to check the signal meter taped to the receiver strapped against her chest. Each time the needle rode a little farther right.

The plain offered nothing to hold scale. A low rise could be twenty meters away or two hundred. Their own shadows had been erased. Mara stopped trusting her eyes and watched the machine nose, the GPS, the tow line to the radar sled. The rest was guesswork and whiteness.

Elin raised a fist. They cut engines one after the other. Silence came down hard, immense and close, with only the ticking of cooling metal and the thin hiss of blown snow over the drifts.

Signe dismounted and went straight to the radar unit. “We’re over the gamma extension.”

Mara unhooked the receiver, flexed her fingers, then crouched by the tow sled while Elin dragged the radar transceiver into place. The instrument looked crude from the outside—an orange composite box, cabled to a pair of sled runners carrying the transmitting and receiving antennas—but it had cost more than Mara’s first house and demanded to be treated like a temperamental animal. The batteries had to stay warm. The connectors had to be brushed free of ice. The drag speed had to stay even or the data came back drunk.

Elin stripped one mitten with her teeth and worked the screen controls barehanded, quick and practiced before the cold could bite deep. A gray plot began to crawl across the display as Signe pulled the antenna sled in a straight line marked by two ski poles. Snow squeaked under her boots.

Mara turned in place with the receiver held in both hands. The signal waxed on the right, fell off, rose dead ahead. So close now that the static no longer fully buried the shape of the transmission.

Three ticks.

A burst.

Then, very faintly, the old clipped call sign.

She heard a breath behind it that should not have survived ninety years and a roof of ice.

“Elin.”

“Busy.”

Mara crouched beside her. The radar trace showed the usual stacked bands—surface clutter, denser return, the long fading comb of deeper ice. Then a disturbance, brief but plain, where the layers lost their neat parade and bent around something darker.

Elin tapped the screen with her thumbnail. “There.”

“A rock inclusion?”

“Not this flat.” Elin expanded the segment and frowned. “Could be a void. Small one.”

“Small is enough for a transmitter housing.”

“If a transmitter has been sitting in Antarctic ice since 1938, it isn’t sending us anything.”

Mara did not answer. Signe came back hauling the antenna sled, breath showing white around her scarf.

“Well?”

Elin turned the screen toward her. “Anomaly at eleven meters, maybe twelve. Not big.”

Signe squinted at it. “Cavity?”

“Maybe. Or old fracture fill. The data are filthy in this visibility.”

Mara was already scanning the meter. The needle quivered near the top of the scale. “It’s directly under us.”

Signe heard the signal through the speaker before either of the others spoke. She stiffened and glanced down at the receiver hanging from Mara’s hand.

The sound spilling from it had changed. Not louder, exactly. Less smothered. The static was no longer a broad blanket across the band but a rough fringe around something narrower and more certain. The ticks came clean enough to count in the open air.

Signe held out her hand. “Give me that.”

Mara passed it over.

Signe listened with her head bent, one cup pressed to her ear. Wind worried at the hood around her face. She adjusted the gain, then backed it down sharply. “No.”

“What?”

She looked up at Mara first, then at Elin. “It shouldn’t sound like this.”

Elin wiped the screen with the side of her glove and rose. “Meaning.”

“Meaning if it were coming through twelve meters of ice and whatever junk is in that layer, it should be blurrier than it was at camp, not cleaner.” Signe turned once in place, receiver held out, testing the angle. “This sounds like line of sight.”

Mara let that sit a second. “You can’t have line of sight to something under the ice.”

“I know that.”

Elin took the receiver from her and listened herself. For a moment she said nothing. Her face, under the rimed hood, went flatter than before. “Could be surface reflection.”

“Off what?” Mara asked. “The weather?”

“Temperature inversion. Some freak bend.”

“In a ground signal?”

Elin handed the set back too quickly. “Then interference.”

Mara almost laughed. Not from amusement. From the shape of the denial. “From whom?”

There was no one out here. No station within useful distance, no aircraft, no ship. Even their own camp had dropped behind the white wall as if it had never existed.

Signe drew a slow breath through her nose. “Play it on speaker.”

The little cone crackled as Mara switched over. The sound carried oddly in the blank air. Tick. Tick. Tick. Then the pulse, cleaner than before, and between the bursts a thread of voice—too frayed for words, unmistakably human.

Elin stared at the snow between her boots as though something might write itself there. “Turn it off.”

Mara didn’t.

The next cycle came.

Tick. Tick. Tick.

Then, in a rasp scraped nearly smooth by age and distance: “...help...”

No one moved. Even the machines, cooling behind them, had stopped ticking. The white around them seemed to press inward, attentive.

Signe swallowed. “That wasn’t on the recording.”

“No,” Mara said.

Elin stepped forward and snapped the power switch down herself. The sudden silence had a force to it. “We mark the spot, we log the anomaly, and we go back with a drill team.”

Mara stared at her. “By the time a drill team gets here—”

“By the time a drill team gets here, we won’t be dead under a collapsed roof because you decided to dig with a snow shovel.”

“I’m not saying dig blind.”

“Good. Because I’m not asking.”

Mara looked out across the flat white at nothing. The source point had become absurdly precise in her head: not a place in Antarctica but this meter, this patch of crust, this breath of air. To come this far and stop at the skin of it felt unbearable.

Signe shifted from one boot to the other, listening to something none of them could hear now that the radio was dark. “Mara.”

“What.”

“The surface.”

Mara followed her gaze. At first she saw only the usual wind-carved texture: low ribs, knife edges, little glazed hollows. Then one detail broke away from the rest. Five meters ahead, a line no wider than a bootlace ran across the snow crust in a shallow curve. Not a drift seam. Too straight in one section, then gently hooked. She walked toward it before Elin could tell her not to.

“Elin.”

“I can see it.”

The line widened as she approached, a hairline opening exposing a blue so dark it looked black. Snow had sifted into it and fused. She crouched, brushed gently with the back of her glove, and more of the shape emerged: a narrow crack, fresh enough that the edges were still sharp.

Signe came up on her left. “Was that there on the way in?”

“No.”

Elin stayed where she was, which meant she was worried. “Back off it.”

Mara set the receiver down and lay flat, spreading her weight. The cold came through immediately, hard as a fist through the front of her suit. She pressed one goggle lens close to the opening.

At first she saw only blue depth, the compressed jewel color old ice kept hidden from the sky. Then, lower, darkness. Not the clouded opacity of dense glacial ice. Space.

“There’s a cavity,” she said.

Elin shut her eyes once. “Of course there is.”

“How deep?”

Mara angled her head. The crack was too narrow. Her own breath fogged the lens. “Can’t tell.”

Signe had the probe pole out before Mara heard her unzip the side sleeve. She screwed together two aluminum sections and extended it toward the opening.

Elin swore. “No.”

“We need depth.”

“We need not to stand on top of a lid.”

Signe paused. Looked at Mara. Then, very carefully, went down on one knee and fed the pole into the crack. It slid easily for a meter, two. Then farther.

Her face changed.

“How far?” Mara asked.

Signe did not answer right away. She was watching the graduations vanish. “Six meters.”

Elin’s voice came very flat. “Bring it back.”

The pole slipped another half meter under its own weight before Signe tightened her grip. “Seven.”

“Bring it back now.”

She did. The sections came out rimed and dry except at the tip, which carried a smear of something granular and white, finer than surface snow. Hoarfrost, maybe. Or drift from below.

Mara pushed herself up to sitting. “It’s a roof over an air pocket.”

Elin spread both hands as if presenting the obvious to a difficult class. “Yes.”

“And the signal’s coming from inside it.”

“Or through it.”

“Either way—”

“No.” Elin’s jaw flexed once. “We have the location. We know there’s a void. That is already more than enough reason to return with proper gear.”

Mara got to her feet. Snow clung to the front of her suit. “Proper gear from where? McMurdo? Christchurch? You think they send a rescue package because we say a dead radio spoke to us from a hole?”

“They’ll send because the radar found a sub-ice cavity in an unsurveyed sector.”

“And they’ll close the area before we get within ten kilometers of it again.”

The two of them stood with the crack between them and the dead receiver at their feet, like an instrument placed between hostile witnesses.

Signe bent and switched the radio back on.

The signal burst from the speaker so suddenly all three flinched. Gone was the distant, half-lost quality from camp. The call sign struck hard and clear enough to make out consonants. Under it, a wash of static. Under that—

—a voice, ragged but immediate, as if speaking from the next room through a bad wall.

“...hear me...”

Elin’s face went white under windburn. “Turn it off.”

Signe did not. She was staring at the crack. “It’s coming up.”

Mara heard it too now, not from the speaker alone but from somewhere under the soles of her boots: a thin, almost musical trembling, too regular for strain noise, too steady for wind. The ice itself seemed to be carrying the signal.

She dropped to one knee and put a glove against the surface.

A hum. Faint. Human-made, or near enough to trap the mind into hearing it that way.

“Elin.”

Elin had already moved. She snatched the coil of safety rope from the sled and began clipping harness lines with blunt, furious efficiency. “Everybody clip in. Now.”

Mara obeyed without argument, which told all of them how bad it was. Carabiner. Waist loop. Quick tug check. Signe clipped last, one eye on the crack as it spread another centimeter with a sound like a fingernail drawn slowly through silk.

None of them spoke.

The fracture ran fast after that.

It did not explode. It traveled.

A dark line shot outward from the original seam, forked left, then right, sketching a shape under the drift with sick precision. The snow crust sagged between the branches. One of the snowmobiles rocked as the front ski dropped half an inch.

“Back,” Elin said, too calm.

They took one step.

The whole field answered with a low report from below, not sharp like a gunshot but deep and resonant, as if some enormous door had been struck in the dark.

The front of Mara’s boot punched through.

She threw herself sideways on instinct. The crust under her left knee held for the barest fraction, then gave way. Snow collapsed in slabs. The receiver slid toward the opening, struck an edge, vanished.

Signe screamed Elin’s name.

Elin braced, drove both heels in, and hauled on the rope as the surface dropped under them. For one impossible second Mara was hanging half over open blue, looking down into a widening throat of ice with blown snow pouring into it like grain.

Then the line went taut across her hips hard enough to bruise.

The anchor failed.

One of the buried pickets tore loose with a flat metallic snap. Elin pitched forward onto her stomach, clawing at the surface. Signe lunged for the radar sled, missed, caught a tow strap, and was jerked off her feet as the crust she lay on sheared free in a single white plate.

Everything moved at once.

The remaining snowmobile lurched backward, rear track screaming, then slid nose-first into the split. The rope yanked all three sisters together. Mara caught a flash of Elin’s eyes wide in a mask of frost, Signe’s open mouth, the orange radar housing tipping end over end.

The world dropped.

Not cleanly. In pieces. Falling snow, broken crust, a hammering tangle of rope and limbs and hard impacts cushioned by packed drift that gave just enough to keep bone inside skin. Mara landed shoulder first, rolled, filled with white, and struck stillness so abrupt it seemed manufactured.

For a second there was no sound in her except blood.

Then someone was coughing. Someone else was swearing in short, furious bursts.

Mara opened her eyes.

Above, the fracture hung as a ragged wound fifty feet up, a long slit of daylight blowing white into the chamber. Snow sifted steadily from the torn edges. One snowmobile was gone entirely. The other protruded nose-down from the wall at an angle, half-buried, one rear ski spinning uselessly before finally winding to a stop.

The air on her face was wrong.

She sucked in a breath and jerked upright, disoriented by the warmth of it. Not warm like indoors, not comfortable, but far too mild for what lay overhead. Her hood suddenly felt suffocating.

“Elin?”

“Here.” Hoarse, close. “Don’t stand under anything vertical.”

“Signe?”

A muffled curse from a drift to the right. Then a gloved hand burst out of the snow and waved obscenely. Mara crawled to it and dug until she found Signe’s shoulder and hauled. Signe came out spitting crystals, goggles askew, radio headset cord looped around one arm like seaweed.

“You kept the headphones,” Mara said, breathless.

Signe laughed once, half-hysterical. “Priorities.”

Elin was already on her knees checking the rope for cuts, fingers moving fast over the sheath. Her hood had fallen back. Damp hair clung darkly to her temples. She looked up toward the crack high above them, then around the basin.

The place had the shape of a buried bowl, steep-sided and wider than Mara expected, its floor banked with old fallen snow. Beyond the slope where they had landed, an opening yawned in the far wall: not a break in fractured ice but a passage, low and black, with a faint wash of bluish light somewhere deep inside it.

Then the speaker on the receiver—somehow still alive under the drift where Signe had dragged it free—gave three crisp ticks.

No static now. Barely any.

The voice that followed was clearer than a whisper in a church.

“Help.”

All three of them turned toward the dark opening in the wall, where the blue light seemed to pulse once, like something breathing.

“Don’t go in there yet,” Elin said.

Mara had already taken three steps toward the blue-lit opening before the words caught her. She stopped on the sloped snow, boots sinking to the ankle, and listened.

The chamber had its own sound now that the crash and shouting were over. Not wind. Not the hiss of drift through a torn seam overhead. Something thinner and steadier. A trickle. Water, impossibly, moving somewhere out of sight.

Signe bent over the receiver in her mitts, turning the volume knob with stiff fingers. The headset foam was packed with snow. She slapped it against her thigh, put one earcup to her head, winced, and handed it to Mara.

The signal was close enough to feel indecent. Three ticks. A wash of carrier. Then breath on the line, or something that imitated breath.

“Help.”

No fade. No atmospheric warble. It sat in Mara’s ear as if a speaker were hidden behind the dark opening.

She gave the headset back. “It’s right there.”

“It is not right there.” Elin pointed up with two fingers. “First we check injuries. Then we check anchors. Then we decide how dead we are.”

“Comforting.”

“Functional.”

Mara did a quick inventory because Elin was right and because the warmth in the basin was making her judgment feel oddly loose around the edges. Left shoulder bruised, neck stiff, no knife-blade pain on breathing. She flexed both hands inside her gloves. All the fingers answered. Signe had blood dried under one nostril and a split seam across one knee where the outer shell had abraded white, but she stood squarely enough. Elin’s lower lip was cut. Her right sleeve hung dusted in snow from shoulder to wrist where she had landed hard, though she was favoring nothing.

Above them, daylight poured through the fracture fifty feet up, a torn white strip with soft edges. It made the chamber look less like a cave than the inside of a broken tooth: blue walls, granular snow, trapped brightness. Fine crystals still spilled from the lip.

Elin unhooked her harness line and hauled at it. The rope slithered free of the slope, then came taut, rising up the wall to where one anchor had somehow held.

“Good,” she said under her breath.

“Good?” Signe said. “You and I define that word differently.”

“If one picket stayed set, we may get one person up. Maybe gear after.” Elin looked toward the half-buried snowmobile canted nose-first in the wall. “If the frame isn’t twisted, maybe we salvage tow line too.”

Mara turned in place slowly, taking the basin in. The snow floor ended twenty feet beyond them at a dark margin where old ice gave way to rock. Actual rock, not windblown grit frozen into the surface. A black ledge shone with moisture. Water ran along it in a thread no wider than a bootlace, dropping into a narrow crack with a bright, patient sound.

She stared at it until Signe came to stand beside her.

“That can’t be right,” Signe said.

Mara crouched and touched one gloved finger to the trickle. Liquid beaded on the fabric. Not slush. Not brine half-frozen into grain. Water.

She rubbed thumb and forefinger together. The glove came away slick.

Behind her, Elin said, “Don’t touch anything you can’t name.”

“It’s water.”

“Then especially don’t.”

Signe laughed once through her nose. “We’ve reached the stage where water is suspicious.”

Mara stood. The warmth had teeth now. Sweat prickled under her base layer along the spine. Her breath no longer smoked except in faint wisps when she exhaled toward shadow. She unzipped the throat of her parka an inch, then another.

Elin saw it and frowned. “Leave your shell on until we know the air.”

“The air is making me cook.”

“That isn’t data.”

“It’s enough.”

She pulled one glove off with her teeth and pressed bare fingertips against the ice wall nearest her. Instead of the killing bite she expected, she felt cold the way cellar stone is cold in summer. The shock of the wrongness ran through her more sharply than any chill could have.

Signe was already wrestling her hood back. Damp blond hair stuck to her cheek. “It’s like a bad greenhouse.”

“Bad how?” Elin asked.

“Like the kind with something dead under the bench.”

They all went still.

There it was beneath the clean mineral smell of broken ice: a rich damp note, almost vegetal. Wet earth if wet earth could survive here. Mara looked toward the passage again. The blue light inside it was stronger now that her eyes had adjusted, not a single source but a dim suffusion that touched the edges of stone.

Elin followed her gaze and spoke before Mara could move. “We are not chasing a voice in an unknown cavity while tied together like laundry.”

“No,” Mara said. “We’re checking whether we can get out before the roof decides for us.”

That at least held. They worked because work was better than standing in the wrong air thinking impossible thoughts.

The slope up to the wall was unstable old fall packed hard under fresh powder. Mara and Signe dug around the snowmobile with shovel blades and gloved hands until they exposed part of the rear rack and one side panel, stove-red beneath a crust of white. Elin tested the machine’s weight, then the angle of the embedded nose.

“Leave it,” she said. “If it shifts, it takes half the wall with it.”

They stripped what they could reach: emergency bag, clipped fuel bottle, a coil of accessory cord, one crampon pouch, med kit. One ski was gone. The windshield had cracked into a spiderweb. Signe found a flare tin wedged under the seat and held it up like treasure.

“Excellent,” Elin said. “Now if the cave attacks morale we’re prepared.”

The rope to the surviving anchor hung down the wall at a slight angle, disappearing through the slit above. Elin tied in first. She knocked steps into the hard slope with the adze of her ice tool, front-pointed onto a rib of blue ice, and climbed until she reached the vertical section.

From below Mara watched the line of her body go from competent to strained to deliberate. The ice there was too smooth, too old. Elin got both crampon fronts to bite, stood up on them, and reached.

The rope trembled.

“Can you see the lip?” Mara called.

“No.”

“How far?”

Elin did not answer at once. She shifted higher a few inches, scraping for purchase. Then, clipped flatly: “Far enough.”

Another foot. Another pause.

A rifle crack snapped through the chamber. All three looked up. A slab the size of a duffel broke from one side of the fracture and shattered past Elin, bursting white at the base of the wall. She tucked in hard, helmet against the ice.

“Down,” Mara shouted.

“Not yet.”

“Down.”

Elin hung there one second more, judging something none of them could see. Then she descended with controlled speed, boots skidding in the steps she had cut. When she hit the snow floor she turned away from them, yanked off one glove, and pressed thumb and forefinger into her eyes. Just once.

“No route,” she said. “The lip has undercut. It’s shedding.”

Signe blew air through her teeth. “Meaning?”

“Meaning if one of us gets near the top and that edge calves, she dies before she falls.” Elin pulled the glove back on with her jaw tight. “We can try later if the shape settles.”

Mara looked up. The crack was still wide enough to paint a clean oblong of daylight on the opposite wall. But the edges were moving. Not fast enough to see in motion, only enough that when she blinked and looked back, the geometry had changed. Snow plastered one side. A suspended tongue of ice leaned lower than before.

“Later may not be a thing,” she said.

No one argued.

The warmth kept building in their heavy gear. At first it was simple discomfort, then dizziness threaded into it. Mara felt it when she bent to tighten the accessory cord around a pack and rose too quickly; the chamber lurched sideways, corrected, and left her heartbeat dragging behind. Signe sat down abruptly on the emergency bag and started tearing at her parka zipper with both hands.

“I’m going to be sick,” she said.

Elin crossed to her at once, not to comfort but to help strip layers with efficient violence. Mitten clips snapped. Hood off. Goggles up. The plume of heat that rose from Signe’s neck was visible only because the air near the floor still held pockets of chill.

“Base layer only,” Elin said. “Keep shells dry. We may need them again.”

Mara had already peeled off her own outer mitts. Her inner gloves were soaked at the fingertips from the water. She shrugged out of her parka and the relief was so immediate it was almost shameful. Cold-country habit made her flinch, waiting for exposure to punish her. It didn’t. In fleece and thermal layers she was still too warm.

Elin lasted another minute before she swore under her breath and stripped her parka too. They laid the three coats on the snowbank away from the watercourse, bright as signal flags in the dim chamber.

Without the bulk of the gear, the place pressed closer. Mara could hear the water more clearly now, and another sound below it, intermittent and soft: drops landing on leaves. Leaves, her mind supplied before she could stop it.

She picked up the receiver. “Check the signal.”

Signe took it, dialed the gain down, then back up. The needle quivered near the top stop. “Stronger than before. Much stronger.” She angled the set toward the dark opening. The meter climbed and held. Away from it, it dropped at once. “That’s our line.”

“Elin.”

“I know.”

But Elin did not tell them to move. She walked instead to the rock ledge where the water ran and knelt carefully. The black stone under the film of melt was banded faintly with green and rust-colored streaks. Mineral deposits, Mara thought, though from what system she could not say. Elin held the back of her fingers near the stream without touching.

“It’s warmer near the floor,” she said. “Not by much. Enough.”

“So there’s heat below us,” Mara said.

“There’s heat somewhere. Geothermal pocket. Volcanic remnant. A sealed cavity with trapped exchange.” Elin’s voice was clipped, building hypotheses the way some people built barricades. “The overlying ice insulated it. The void stayed open. Water found paths through rock.”

Signe leaned her head back and looked toward the torn sky. “You’re making it sound normal.”

“I’m making it sound possible.”

Mara stepped to the mouth of the passage. The transition from the basin to the tunnel was abrupt. Snow thinned, then vanished. Stone took over underfoot, slick in patches where moisture had dried to a gloss. The blue light came from clusters of growth fixed to cracks in the walls—flat fronds and nodules and stringy things like roots hanging from the ceiling. Their color was not electric and not soft either, something between moonlit milk and a welder’s arc seen through smoke.

She reached out and stopped short of touching one.

The nearest frond pulsed faintly.

Not an illusion. Not her eyes tiring. A slow brightening, then dimming, as if sap moved through it.

Behind her, Signe said, very quietly, “Mara.”

She turned. Signe was staring not at the plants but at the chamber walls beyond them. Once Mara followed her sightline she saw it too: along the lower edges where snow met stone, pale threads and lichen-like mats spread in irregular fans, tiny points of blue nested in them like embers under ash. Life, in a place the maps had left blank.

A hidden world sealed beneath Antarctica, some part of her thought with a child’s helpless clarity, and another part answered at once: yes, and it can still kill you.

Elin came to the threshold and stood with one hand on either side of the rock, steadying herself or claiming the fact of it. “No bare skin on anything,” she said. “No food until we know if the air’s doing something. We mark our route. We don’t separate.”

“Route to where?” Signe asked.

Elin looked back toward the wall they had fallen through.

The chamber had darkened.

Not much. Just enough that the rectangle of daylight above had gone from hard white to a dimmer, colder blue. Snow still sifted from the lip, but now in intermittent curtains as the edges slumped inward. Mara watched a narrow fin of ice rotate soundlessly and vanish into the gap.

“We wait ten minutes,” Elin said. “If the opening holds, I try the wall again with lighter load. If it doesn’t—”

She stopped.

The deep report from above rolled through the basin with the same door-struck resonance as before, only closer now, inside the walls. Mara felt it in her feet. A seam zigzagged across the ceiling ice, throwing white dust.

“Sides,” Elin snapped.

They moved without speech. Mara caught Signe by the sleeve and dragged her under the shelter of the rock at the passage mouth. Elin threw herself beside them a heartbeat later.

The sound that followed was not one collapse but several. Sharp snaps. A rushing spill. Then a dense impact that made the floor jump under Mara’s palms. Snow burst outward across the chamber in a pale wave, peppering the stone. The blue growth on the wall fluttered in the disturbed air and steadied.

Silence came back by pieces.

Mara rose first into the settling haze. Where the opening had been, there was now a blocked throat of broken ice and packed snow. A few seams of gray light still showed between tilted slabs high up, thin as knife cuts.

Signe pushed past her. “No.”

She started up the slope at once, slipping, using both hands. Mara went after her. By the time they reached the base of the new fall, Elin was already there, kicking at the debris, testing what was solid and what only looked solid. It was worse up close. The collapse had plugged the narrowest part of the chimney with interlocked chunks the size of refrigerators, then dumped tons of powder and hard slab around them. Air hissed through somewhere above, but faintly now.

Signe drove her gloved hands into a gap and dug until the snow packed her sleeves. “There’s space. Help me.”

Elin caught her wrist hard. “Stop.”

“We can clear it.”

“With what?”

“Our hands, Elin, what do you think—”

Elin shook her once, not cruelly, just enough to break the line of panic. “If we pull the wrong piece, the rest comes through.”

Signe’s mouth worked. She looked up through the thin gray seams, as if she could force them wider by will. “We can’t stay down here.”

Mara put her palm against one of the slabs. It was colder than the chamber had any right to be, the old cold preserved inside it. Beyond, somewhere high in the blocked chimney, daylight survived in hairline leaks. Already they seemed to be dimming as spindrift sealed them.

The receiver in Signe’s dropped hood gave three ticks.

All of them turned.

No one had touched it. It lay half-buried where it had slid from the emergency bag, the speaker aimed toward the passage. The signal came through clean and intimate in the hush after the collapse.

Not just the one word this time.

“Can you hear me?”

The voice was male. Tired. Educated in a way that belonged to old recordings and nowhere in their camp. Beneath the words a faint hum carried, steady as current.

Mara looked from the blocked opening above to the blue mouth in the rock.

Elin picked up the receiver slowly, as if lifting something alive.

Another soft pulse moved through the growth along the tunnel walls, a breath passing from one cluster to the next, deeper into the dark. The light seemed to beckon and warn in the same motion.

Above them, the last visible seam of day narrowed to a thread. Then to a pin. Then it was gone, and the chamber belonged entirely to the blue.

Elin did not ask who wanted to go first.

She pulled a chem pencil from her chest pocket, snapped it against her glove to wake the core, and crouched at the passage mouth. The blue light lifted the planes of her face into something severe and carved. “Pack check,” she said. “Say it, don’t nod.”

Mara shifted her shoulders under the harness straps. The webbing was damp where snow had melted into it. “Receiver. Coil of line. Two headlamps.”

“Neither of which we use unless we have to,” Elin said.

“I know.”

Signe dragged the emergency bag closer with the heel of her boot. “Med kit. Flares. Stove. Batteries that may or may not be worth carrying if the cold killed them.”

“It didn’t kill them,” Mara said.

Signe gave her a thin look. “You tell me what any of this place kills and I’ll write it down.”

Elin tore a strip from the orange survey tape and tied it around a nub of stone at the entrance. The color looked obscene in the blue wash, a flag from the normal world left at the border. “I lead with the map. Mara on signal. Signe in the middle. If one of us stops, all of us stop.”

The receiver clicked in Mara’s hand, then gave the three measured ticks. The pulse answered from the walls.

Not sound. Light.

The fronds nearest the opening brightened in a slow run, each blade kindling at its tip and pouring color down into the stem. It was not blue exactly. Blue at first glance, yes, but layered under with green and a hard milk-white at the edges, the way glacier ice holds more than one color when you look too long. The glow went deeper into the tunnel in a receding sequence, a trail being touched into life.

Signe stared. “That was us?”

“Or the radio,” Elin said.

Mara lifted the receiver closer to her ear. Under the ticks lay the low current-hum, steady enough now that it seemed to have shape, almost a note. “Only one way to sort it.”

She ducked into the passage before either of them could answer.

The ceiling dropped at once. Not enough to crawl, but enough that they had to hunch under it and angle their packs. Rock pressed close on the left, rough and black, while the right wall was skinned in old ice clouded with trapped grit. A trickle of water moved somewhere beyond sight, making a thin glassy sound. The floor under the fresh drift was stone, not snow, and the stone sweated. Warm moisture soaked through the knees of Mara’s outer layer when she steadied herself on one hand.

By the tenth step she had to stop and wrench open her parka.

Heat rolled around inside the clothing she had worn all day to survive the surface. It had nowhere to go. Her own sweat had turned sharp in the sealed air, rank wool and salt and the rubbery smell of heated waterproofing. Elin had already unfastened to the sternum. Signe tore one glove off with her teeth and wiped her upper lip.

“No bare skin,” Elin said at once.

“It’s thirty feet from where you said it,” Signe said.

“Then put it back on.”

Signe did, violently. The movement stirred the nearest vines. They hung in ropes from a crack in the ceiling, translucent as peeled celery and lined with nodules that gave off a weaker light than the fronds. At the gust of motion they contracted almost imperceptibly. Not enough to call it movement, if Mara had seen it from the corner of her eye. Enough when she watched directly.

She reached out.

Elin’s pencil halted on the page of her waterproof notebook. “Mara.”

Mara touched the vine with one gloved fingertip.

The reaction traveled away from her hand in both directions. Every bead along the hanging rope flashed brighter, then the neighboring rope, then the nearest plate of fungus where it clung to the rock like a shelf of thin porcelain. The shelf glowed through from within, veins lighting first, edges second. The whole patch gave off a damp mineral smell, not plantlike at all. Copper. Wet limestone. A trace of something sweet and spoiled under it.

Signe made a sound that was half laugh, half recoil. “It felt me.”

Mara rubbed thumb and forefinger together through the glove. The surface had been slick, faintly warm. “Pressure response.”

“To a radio signal?” Elin asked.

“To anything.” Mara looked down the length of the tunnel where the glow was still fading from one growth to the next. “Maybe.”

Elin drew a quick mark on the page: entrance, narrowing passage, hanging growths. Her handwriting remained clean even in gloves, the habit of years. “We don’t touch more than we need to. We don’t eat it. We don’t scrape samples until we know whether it aerosolizes.”

Signe bent close to a cluster growing from the ice. They were shaped like folded ears, translucent white with electric ribs. “You say the good news first for once.”

The passage turned, shouldered left, and widened enough that they could straighten. Mara felt the relief in her spine like a separate sensation. She stripped off one glove, then stopped under Elin’s stare and used her teeth instead to drag her zipper lower. Steam lifted from the collar of her fleece. Beneath the warm, wet air was a deeper smell now, a living one. Moss after rain. Cracked melon rind. Mud pulled from the bottom of a pond.

The receiver gave another sequence. Tick. Tick. Tick.

The growth ahead answered, brighter than before.

Elin looked up from the notebook. “All right.”

Mara did not pretend not to know what she meant. “You heard it.”

“I saw it.” Elin moved past her a pace, studying the walls. “When the signal hit, it ran along the right side first.”

“The side with more of the stuff on it,” Signe said.

“Still.”

They kept going. Elin marked their route with pencil on stone where rock took the line and with survey tape where it did not, stingy lengths knotted low so they would not brush loose. The tunnel sloped down by degrees. Water collected in the hollows, enough to darken the stone and leave rims of pale deposit. Here and there the black rock broke through the ice in blunt shoulders, and every shoulder carried growth. No two patches matched. Some spread in frilled fans no thicker than paper. Some formed velvet mounds stippled with light. One stretch of wall was latticed in roots or vines or something pretending to be one and not the other, their tubes carrying pulses of color up and down as if liquid light moved inside them.

Signe saw things first when they changed.

“Stop,” she whispered.

Mara froze, one boot lifted over a crack in the floor. “What?”

Signe was not looking ahead. She was looking behind them.

The tunnel they had just crossed had dimmed.

Not gone dark. The fronds and shelves still glowed, but at a lower grade, as if someone had put a hand over a lantern. The section before them held its brightness. The light there sharpened the wet edges of stone, found every drop on the wall, turned the ice to faint milk.

Elin slowly turned in place to compare. “Don’t move.”

No one did.

The glow steadied.

Mara raised the receiver and shifted the tuning a hair with her thumb. Static roughened. The hum deepened. Instantly the vine nearest her brightened, and the brightness leaped forward three yards, five, ten, tracing the tunnel’s next bend before settling back.

Signe let out her breath. “It likes that.”

“Or hates it,” Elin said.

Mara tuned back. “Response is strongest when the signal is strongest.”

“Meaning the transmitter is wired to a greenhouse.”

Mara almost said impossible, then let the word die. They had fallen through Antarctic ice into warm dark threaded with glowing growth and a man’s voice from 1938. Impossible had lost all force.

Signe crouched beside a patch of low fungus and moved her bare-knuckled glove close without touching. The surface quivered. Not visibly at first; Mara saw it only because the light strobed a fraction faster along the filaments. Then the tiny cups at the patch’s center opened wider, each one no larger than a lentil, showing silver wetness inside.

“Back,” Elin said.

Signe backed away at once. “I didn’t touch it.”

“It reacted.”

“So do I.”

Elin held out a hand. Signe gave over the ice probe without being asked. Elin extended it and brought the metal tip slowly toward the patch.

Nothing.

Closer.

A dull brightening at the outer rim.

Closer still, until the tip nearly grazed the cups.

The entire patch flared white-blue so hard it hurt Mara’s eyes, then subsided in a rippling wave that traveled up the wall and into the vine-net above them. Farther ahead, something answered in the dark: a distant soft ignition, then another.

Elin drew the probe back. “Heat, maybe. Conductivity. Movement of air.”

“Presence,” Signe said quietly.

No one corrected her.

They passed into a chamber no bigger than a railcar, the roof lifting overhead. Here the growth was thick enough to make shadows. Great fronds rose from cracks in the stone floor, each one ribbed like a fern but fleshy at the stalk. Fungal shelves climbed a boulder in overlapping tiers, from thumb-size to broad enough to cup a face. Vines looped between them, and high on the ice wall hung bulbs clear as glass floats with threads of light coiling inside. Some had condensed droplets under them that fell every few seconds into a shallow basin cut by ages of water. Each drop rang on stone.

Mara stopped listening to her own breath and heard another pattern underneath the dripping.

Not the radio. Not quite.

A faint rustle, all around them, though nothing with leaves could make it. The fronds were flexing. Bending a little toward their warmth, perhaps, or toward the receiver in her hand. As Signe edged left, the nearest stand inclined that direction by a finger’s width. When Elin stepped back to sketch the chamber, the bulbs above her brightened one by one, following the line of her movement.

Signe saw it too. “They’re tracking us.”

Elin kept drawing. “No sudden motions.”

“That wasn’t sudden.”

“That’s not instruction for them.”

Mara moved to the center of the chamber and crouched beside the basin. Water here was unmistakable, clear enough to show black stone under two inches of depth. A skin of mineral traced the edge in pale green. She put the back of her glove near it. Warm. Not hot, but warm enough that every instinct she had built on the ice wanted to reject the fact.

The receiver hummed against her wrist bones.

She lowered it toward the water.

The basin lit from below.

The clear bulbs overhead flared in answer and sent moving threads through their cores. The fronds around the pool drew brighter along their central ribs. A path appeared on the chamber floor where she had not noticed one before: not a path made by feet, but a route of denser growth, each low mat and climbing filament kindling in sequence across the stone to a split in the far wall.

Elin stopped sketching.

The split was narrow, almost hidden behind a curtain of drooping vines. Beyond it the tunnel divided at once into three branches: left, center, right.

Only the center shone.

The left branch held scattered dim patches, enough to show wet rock and nothing more. The right branch was darker still, blue fading almost to black within ten feet. But the middle throat blazed with patient intensity, every frond and fungus body alive with light, as if fed by something under the stone.

Signe took a step toward it and the brightness rose.

“Oh, no,” she said, voice barely audible. “No. That is not nothing.”

Elin went to stand at the fork. She did not cross into any branch. Her pencil hovered over the notebook, forgotten now. “Could be airflow.”

“Airflow that chooses,” Signe said.

“Temperature gradient.”

“Then why does it wait for us?”

Mara stood slowly. Sweat had dried cold between her shoulder blades despite the heat. In the center branch the pulsing matched the receiver exactly now, not almost but precisely: three ticks, pause, three ticks, pause. She could count it in the walls.

She turned the gain down.

The middle branch dimmed.

She turned it up.

Light rushed back through the growth so quickly that the vines near the split shivered against each other with a sound like wet paper rubbed together.

No one spoke.

Elin held out her hand without taking her eyes from the tunnel. Mara gave her the receiver.

Elin tested it herself. Lower. Dimmer. Higher. Brighter. She tried stepping toward the left branch with the signal strong. The growth at its mouth barely responded, only a feeble glimmer around one knot of fungus. She moved to the right. Less than that. She faced the center again, and the whole passage came awake as if some current had found the proper wire.

Signe laughed once, raw and humorless. “So much for natural.”

Elin did not answer immediately. She was listening, head slightly bent, receiver pressed to one ear. The old hum threaded through the ticks. Under it, Mara thought she heard a grain of voice trying to form itself and failing.

“At least part of it is natural,” Mara said. “It grows from the rock. It’s fed by water. There’s mineral deposition all over the roots. But the response—”

“Is trained,” Signe said.

“Or selected,” Elin said.

They looked at her.

She lowered the receiver. “If something lives in a place with a standing signal long enough, it changes around it. We’ve seen bacteria do it around vents. We’ve seen fish use electrical fields. This could be growth that happened to respond, and anything that responded in the useful direction survived.”

Signe rubbed both hands over her face. “Useful to whom?”

That landed and stayed.

Mara stepped to the edge of the center branch. The air that came from it was warmer by a degree or two, enough for her damp shirt to cling tighter. She could smell deeper water there, and metal under it, the dry penny tang of old machinery. The tunnel floor showed a faint trough worn into the stone, not by boots, not recent, but repeated passage of something over a long time. Around the trough the fluorescent mats grew thick and untrampled, soft-looking as algae.

She pointed. “This one goes where the signal goes.”

“Elin,” Signe said, and there was the first real plea in her voice since the collapse, “if something made a path, that doesn’t mean we take it.”

Elin slipped the notebook back into her pocket. Her face had that stripped look Mara knew from weather calls and bad ice, when the decision had already been made and she was only testing whether anyone else could bear to hear it.

“We don’t split,” Elin said. “We don’t outrun the light. If any branch darkens around us, we stop. If anything in here changes faster than we can understand, we fall back to the last marker.”

Signe looked at the glowing center and not at either sister. “That isn’t a no.”

“No,” Elin said. “It isn’t.”

She handed the receiver back to Mara.

The moment Mara’s fingers closed around it, the center branch brightened again, not just ahead but underfoot, one pulse stepping out after another into the dark. Ready. Expectant. Like a runway. Like bait.

Far down the tunnel, beyond where the glow thinned into distance, something answered with a single pale flare and went out.

Signe heard it. Mara felt her stiffen.

Elin drew a long breath through her nose. “Mark this fork.”

Signe tied the orange tape with clumsy hands.

When they were done, none of them moved for a second. Three women in half-open polar gear, sweating under the Antarctic ice, facing a lit corridor that had chosen them back.

Then Mara raised the receiver, and the garden showed them the way.

The first eyes were level with Mara’s knee.

She stopped so hard Elin walked into her pack. The receiver in Mara’s hand gave its three dry ticks, and the light in the walls rolled ahead another few feet, enough to show a cluster of low shapes gathered beside the trough in the stone.

Not rocks.

They were the color of old wax, almost without shadow except where the blue growth painted hollows under rib and shoulder. Six limbs, folded close. A narrow body carried low to the ground on four walking legs, while the front pair—smaller, jointed inward like hands that had forgotten their trade—rested lightly against the mat of glowing fronds. Their heads were blunt and smooth, with no visible ears, just a flaring slit on either side of the neck that opened and closed as they breathed. The eyes were the worst part. Too many lids. Clear inner membranes flicking sideways over black, polished pupils.

Signe made a sound in her throat.

One of the creatures tipped its head. It rose another inch, not in alarm but in attention, and the movement traveled through the little group in sequence. A dozen heads lifted. A dozen sets of eyes fixed on the sisters.

Mara’s hand went to the flare pistol clipped to her harness.

“Don’t,” Elin said, very quietly.

“They’re in the path.”

“They haven’t moved.”

The nearest creature took three careful steps toward them.

Its feet were soft on the stone. The front limbs unfolded and touched down, not bearing weight, just testing. The small hands had four white fingers each, translucent at the tips. They brushed the glowing growth and the fronds dimmed, then brightened again after it passed.

Mara eased the flare pistol free anyway. In this light everything looked half-made, skinned, wet. The thing advancing toward them carried its own wrongness with complete calm.

Signe reached past Mara and pushed the barrel down.

“Look at the sides,” she whispered.

The creature’s narrow flanks moved with quick, even breaths. Not a charge. Not bracing. It lowered its head to the trough worn in the floor and licked once at a bead of water gathered there, tongue black and thin as ribbon. Another two behind it had already bent to graze, scraping the fluorescent mat with combed lower jaws.

Elin took one slow step forward, making herself larger without rushing. “Back.”

The word meant nothing, but her posture did. She lifted both gloved hands. The lead animal froze, then rocked back on its rear limbs. Its front hands rose against its chest, fingers flexing. Curious. Watching.

Mara felt the pressure behind her eyes that had come with the heat, the bad air, the throb of the signal. Every old rule she knew was useless here. Aboveground you judged bulk, antler, tooth, the lay of fur, the season, distance to cover. Here she had a smooth thing the size of a dog with too many joints and nursery-black eyes, and her body wanted a clean answer from it.

The receiver ticked again. The wall-fronds answered in a pulse that slid over the creatures’ backs.

At that, three more emerged from the dark behind the first cluster. Then two smaller ones, moving close to the belly of a larger animal. They nosed at the glowing mats and at each other. One pressed its face to the nearest adult’s side as if seeking milk, though there was no udder that Mara could see.

Signe’s breath let out. “Young.”

Mara didn’t lower the flare pistol.

The lead animal came another step, then stopped just beyond the end of the barrel. It stretched its neck, the clear lid flicking over one eye, and sniffed at the air around Mara’s hand. Its nostrils were hidden, but the neck slits widened, tasting her scent. She could smell it now too: warm stone, wet mineral, and a faint sour-green odor like crushed kelp.

Its little hand touched the toe of her boot.

Mara flinched back.

The creature startled harder than she did. It sprang sideways with shocking grace, landing among the others in a scatter of pale limbs. For one absurd second the whole herd—or whatever it was—bounded away not from attack but from the speed of her movement, then stopped at a distance and turned as one.

Watching again.

Signe laughed under her breath, all nerves. “You offended it.”

“Keep your voice down,” Elin said.

“Why?”

Elin did not answer. She was looking past the pale animals, into the tunnel beyond them, where the glow from the walls thinned and thickened in uneasy bands. Mara listened.

At first she heard only the small sounds close at hand: the wet clipping of mouths on growth, the trickle in the trough, somebody’s zipper tab clicking faintly against a carabiner. Then something farther off. Not loud. A scrape, then stillness. Like a knife drawn lightly over stone.

The herd heard it too.

The shift was instant. Heads came up. Neck slits pinched tight. Every body in the group angled the same direction, not toward the sisters now, but back down the tunnel. The juveniles shoved under the adults. One of the larger animals stamped once with a rear foot.

Mara raised the flare pistol again, this time toward the dark ahead.

“Lights off,” Signe whispered.

“No.” Elin’s voice was flat. “If the receiver drops, we’re blind.”

The next scrape came closer. Not scraping exactly. Claws finding purchase on wet rock.

The pale creatures did not flee. They drew together, shoulder to shoulder across the width of the trough, front limbs tucked, heads low. Mara had the wild thought that they were preparing to rush the sisters after all.

Then the tunnel divided itself.

Something long and dark flowed through the band of blue light thirty feet ahead, so fast the eye almost rejected it as a trick. The wall-glow caught on skin that was not scaled and not furred but sleek as seal hide. It moved on six limbs too, though built to a different logic: rear pair heavy and coiled, middle pair placed wide for speed, forelimbs narrow and hooked inward under a wedge-shaped chest. The head rode low, mouth tucked tight under a blunt snout. No eyes showed at first. Then it turned and the blue caught them—two coin-pale discs with vertical slits clenched thin.

The herd broke.

Not outward. Not randomly. They split around the predator before it even lunged, opening lanes through their own number as if drilled. The small ones vanished between adult bodies. Three larger grazers slammed their front limbs to the stone and gave a harsh chattering hiss from their neck slits.

Warning, Mara thought a beat too late.

The dark creature came through them like spilled oil.

Mara fired.

The flare struck the wall above it and burst white-gold, flooding the tunnel with hard light and greasy smoke. The predator veered, more from surprise than fear. In that flare-bright instant Mara saw the mouth open sideways along the jawline, not down, exposing nested needles of teeth slick with luminous paste. One of the pale grazers screamed—a short metal sound—and the predator hit it in the shoulder, driving it to the floor.

“Move!” Elin shouted.

They stumbled backward, boots slipping on damp stone. Mara clawed for the rifle slung across her back, cursing the way the loosened parka bunched at her elbows. The flare burned on the wall, hissing. The herd exploded around the predator in white blurs, not attacking but battering past one another to get clear.

One of them slammed into Signe’s hip hard enough to spin her. She hit the wall and slid, the chem pencil snapping under her boot with a crunch of brittle plastic.

The predator left the fallen grazer at once.

Not feeding. Not killing. Distracted.

Its head lifted from the thrashing pale body and turned toward Signe, who had made a raw sound on impact. The slit eyes widened, catching the flare. The teeth folded out of sight. It crouched lower.

Mara had the rifle half free, safety still on.

Too late.

Elin yanked Signe upright by the harness strap and shoved her behind a shoulder of rock where the tunnel narrowed. The predator came three body lengths in silence and stopped where the herd smell broke under the sharp human stink of sweat, nylon, fuel residue, hot metal.

It tested the air.

The fallen grazer kicked behind it, trying to rise with one shoulder opened to white tendon. The predator ignored it.

Mara found the safety with her thumb. The muzzle shook once before she locked her elbows. “If it jumps—”

“Wait,” Signe said.

She was bent over, one hand braced on her thigh, face gray under the blue light. Her eyes stayed on the animal.

“It left the wounded one,” she said.

“So?”

“So it changed target when I hit the wall.”

The predator moved a step nearer, not directly at them but on a shallow angle, as if choosing ground. The foreclaws opened and closed soundlessly. Behind it, at the edges of the tunnel, the pale grazers had not gone far. Mara could see eyeshine between the fronds. Watching. Holding distance.

Signe pointed without taking her gaze off the dark thing. “The pale ones only came in when we stood still. They backed off from fast movement. This one came to the sound.”

Another step. Head low. The neck did not flare to scent the air like the others. Instead the skull made small corrections, side to side.

Elin understood first. “It hunts by vibration.”

“Or impact,” Signe said. “Weight. Sudden noise. Maybe both.”

The predator twitched toward Mara as she shifted her boot.

Mara froze.

The creature froze too, every muscle locked.

Then, with eerie delicacy, it set one foreclaw down and flowed a little closer.

“Don’t back up,” Signe said. “That gives it more to track.”

Mara almost told her to shut up. The rifle sight trembled over the narrow head. At this range a shot would be ugly in the confines of the tunnel. Ricochet. Deafness. Maybe worse if the ceiling was less stable than it looked. But waiting felt like laying her throat across a rail and listening for wheels.

Elin reached slowly to her belt and unclipped the ice hammer.

Mara hissed, “No.”

Elin’s eyes flicked to hers. “Not at it.”

She crouched by the wall without hurry, every movement stretched thin, and set the hammer head gently on the stone. Then she slid it away from herself by the leash until it lay ten feet out to their left.

The predator’s gaze—or whatever passed for gaze—did not shift.

Signe swallowed. “It wants the strike, not the scrape.”

Elin nodded once. With two fingers she found a loose chunk of ice the size of a fist where meltwater had undercut the wall. She held it up for the others to see.

Mara understood and hated it. If Signe was wrong, the throw would pull the thing into a lunge.

Elin waited until the predator took another careful step.

Then she threw.

The ice struck the far wall behind the animal and shattered.

The reaction was immediate and violent. The predator spun so fast it seemed boneless, launching toward the impact with both forelimbs out. Its mouth opened sideways again. It hit the wall where the ice had burst and raked at empty stone, teeth snapping.

“Now,” Elin said.

They moved.

Not ran. Mara wanted to run more than she had wanted anything in her life, but Signe grabbed the back of her harness and checked her speed to a fast, controlled retreat. Step, step, plant. No stumbling. No crashing metal. Elin came last, watching the animal over her shoulder.

The predator whipped back at the scrape of their boots, head lifting.

It came after them at once.

Mara fired the rifle.

The shot punched the tunnel like a fist. Her ears went flat. The muzzle flash bleached the blue from everything for one savage blink. The bullet struck low, clipping stone and tearing a furrow across the creature’s middle pair of limbs. Dark fluid sprayed the wall, almost black until the growth touched it and flared green at the edges.

The predator shrieked—not loud, but high enough to drill the spine—and launched sideways into shadow.

Not dead. Worse.

The tunnel ahead narrowed into a bend lined with hanging bulbs and white fungus shelves. The receiver in Mara’s fist yelped static as if the shot had shocked it. Its rhythm faltered, recovered, faltered again.

“Keep it up,” Elin said.

“It’s drifting.”

“Keep it up.”

Behind them, nothing.

That was the worst thing in the world.

They reached the bend. Signe slapped one hand against Mara’s shoulder. “Stop.”

Mara stopped by reflex. Elin nearly collided with them.

Signe pointed down.

The trough in the floor divided there. One branch continued straight, wet and dark. The other climbed the outer edge of the bend over a rise of dry stone. The glowing mats were cropped close along the lower route. Intact on the upper.

“The pale ones ate down there,” Signe said, breathing hard. “They use the water path.”

“And?” Mara said.

“And this thing hit from above them. It doesn’t want the same route.”

There it was again. Not seen. Understood in a single nasty click.

Mara swung the rifle toward the upper rise just as the predator uncoiled from a notch in the wall, body flattened to the stone so perfectly she had not known it was there. It launched at face height.

She fired from the hip.

The shot went wide. The report cracked the hanging bulbs overhead; two burst, spilling hot, luminous pulp across Elin’s sleeve. She swore and flung it off. The predator slammed into Mara’s raised forearm instead of her throat, claws punching through parka shell and scoring the hard plate beneath. The impact drove her backward onto one knee.

Its mouth searched for purchase along her arm, teeth sawing at insulation.

Mara jammed the rifle crosswise into its neck and felt strength there that was not large-animal strength, not mass, but cable and whip. It twisted, trying to reach the noise of her breath, the pounding of her body against the floor.

Signe came in from the side with the broken chem pencil clenched like a spike. She drove the jagged end into one pale eye.

The predator let go of Mara and convulsed backward, shrieking soundlessly at first, then with a tearing hiss. Elin snatched the flare pistol from Mara’s chest rig, shoved the muzzle against the thing’s shoulder seam, and fired.

The flare punched through hide and detonated somewhere inside.

Heat slapped all three sisters. The predator thrashed in a wash of white light, smashing itself against the wall, against the floor, coating the stone with burning chemical and its own dark fluid. The smell was rank and sweet and instantly sickening.

“Back!” Elin shouted.

They dragged Mara clear as the creature battered itself twice more and then collapsed in a folding, impossible way, limbs tucking under, hide twitching around the flare’s buried blaze. Smoke poured low along the stone. The fluorescent growth nearest the body dimmed, then went out entirely.

For a few seconds none of them spoke. Mara sat against the wall with her rifle across her lap and watched the thing burn from within. Her forearm throbbed where the claws had hit the plate. If they had been an inch higher, or if she had stumbled instead of braced—

Signe crouched in front of her. “Can you move your hand?”

Mara flexed gloved fingers. “Yes.”

“Good.”

Elin had already stripped off one glove and was checking the rents in Mara’s sleeve, quick and rough. “Outer shell gone. Plate scored. No blood.” Her own sleeve had a luminous smear on it from the burst bulb, glowing milk-blue. She wiped it against the rock until it stopped shining.

From beyond the bend came a low rustle.

All three looked up.

The pale grazers had returned. Not close. Twenty feet back, massed in the tunnel where the flare-light thinned into blue again. They stood with their heads high, black eyes reflecting the dying white from the predator’s body. One limped; another had bloodless-looking tissue peeled from its shoulder where the attack had caught it. The juveniles stayed hidden behind larger legs.

They did not advance on the carcass. They did not bolt from it either.

Just waited.

Signe stood slowly. “See the spacing?”

Mara followed her point. The animals had formed a crescent beyond striking distance, every body angled toward the dead predator but none crowding the front. The injured ones were in the middle, protected.

Elin said, “They know what it is.”

“They know what we are, too,” Signe said. “Or close enough.”

One of the grazers nearest the front lowered its head and tapped the stone twice with a rear foot. Another answered from farther back. A third took up the same rhythm.

Not panic. A pattern.

Mara lifted the receiver. Its three ticks slipped into the space between those footbeats, and for a moment the whole tunnel seemed to listen—to the machine, to the creatures, to each other.

“Curious means distance closes slowly,” Signe said. “Head up. Hands out. They stop when we stop.”

She pointed at the smoking dark body.

“Hostile means it cuts the angle. Goes quiet before it commits. Watches the place you’ll hit, not your face.”

Mara looked at her. There was bloodless blue pulp drying on Signe’s knuckles from the broken chem pencil. Her braid had half come loose. Her mouth was still shaking with delayed fear, but her voice had steadied around the shape of a rule.

Not safety. Rule.

Enough to live on.

Elin rose and picked up the rifle Mara had almost dropped. She checked the chamber, then handed it back butt first. “From now on we read behavior first.”

Mara took it. “And if we can’t?”

Elin glanced down the tunnel where the pale creatures waited in their crescent, and beyond them into the blue dark where anything might already be hearing the flare, the shot, the last thin cries of the thing at their feet.

“Then,” she said, “we learn faster.”

The nearest grazer lifted one narrow hand and touched the wall-fronds. The glow ran past it, deeper down the passage, pulse after pulse, as if something ahead had been told they were coming.

The grazer’s hand left the wall, and the light kept going without it.

Blue poured down the passage in a chain, bulb to frond to wet mineral seam, each patch waking just before the last died behind it. The dead predator smoked at their backs. Ahead, the tunnel bent left around a shoulder of black rock.

“Elin,” Mara said.

“I see it.”

The herd did not follow. When the sisters began to move, the pale animals opened their crescent and made a narrow lane between themselves and the wall. No rush. No panic. Heads lifted, forelimbs tucked close, watching with the fixed attention of deer or judges. One of the larger adults tapped once against the stone after they passed, a dry clack like bone on slate.

Signe glanced over her shoulder. “That felt like permission.”

“Don’t romanticize it,” Elin said. But she kept her own voice low.

They went single file. Mara carried the receiver high against her chest, headphones hanging around her neck so all three could hear the faint three-tick cadence under the static. Elin had the flare pistol in one hand and her ice hammer in the other. Signe walked last with the spare chem light and the broken pencil still clutched like a shiv, though the point had gone ragged.

The tunnel widened by inches, then feet. The air changed first. Less close. Less plant-warm. The sweet rot of the glowing growth thinned under a sharper smell—metal, wet stone, something scorched a very long time ago and never aired out. The walls lost their thick mats of fluorescent fronds. Here the light came from smaller things: pale blisters in cracks, threads sunk inside clear ice, beadlike fungi scattered over rock ledges like dropped mercury.

Mara touched one with the back of her glove as she passed. It shrank into itself.

“No contact,” Elin said at once.

“I barely brushed it.”

“That counts.”

Mara let her hand fall. The receiver ticked. Static lifted and dropped, lifted and dropped, as if the tunnel itself were breathing through the speaker.

The passage dipped steeply, and then it opened.

None of them spoke for the first few seconds. There was too much to take in and not enough light to trust it.

The cavern was long rather than wide, a hollow bitten through alternating bands of old blue ice and black stone. The ice rose in ridged curtains thirty feet high, trapped with ropes of bubbles and ash-dark streaks. In places it had melted back from the rock and frozen again, leaving glossy overhangs and glass-clear folds that caught the bioluminescent light and held it in cold green sheets. Water ran somewhere out of sight. Not a stream. Drips, spills, the occasional thin plink that echoed forever.

Near the center of the chamber stood two iron uprights anchored into a shelf of stone.

Between them sat a machine.

At first Mara thought it was part of the rock because half of it was buried under chalky mineral crust and a beard of white fungal threads. Then the blue pulse crawled over a wheel, a riveted housing, a boxy coil assembly. Rust showed through under the deposits in reddish scabs. A mast no taller than a person leaned at an angle from the back, snapped once and repaired with wire that had furred green.

The signal in Mara’s headset sharpened so suddenly she flinched.

There was no mistaking it now. Not interference. Not reflection.

A transmitter.

Signe let out one breath through her teeth. “Well.”

Elin did not move closer. “Stay wide. We don’t know what around it is load-bearing.”

The floor between them and the machine was a skin of old mineral deposits over stone, broken by mats of low glowing growth and black puddles as flat as polished obsidian. On the far wall, hanging from an iron piton driven into the rock, something pale swayed once in a breath of warm air.

Canvas.

Mara saw the angle of a collapsed tent pole beneath it, then a crate split open and spilling warped tins, then a second piton with a rotten line still tied off in a bowline gone hard as wood.

Human things. Not recent. Not possible.

Signe stepped toward the nearest crate before Elin caught the shoulder of her pack.

“No,” Elin said.

“It’s not going anywhere.”

“Exactly.”

That checked her. Signe stood looking at the sagging canvas, jaw set, then nodded once.

Mara could already see the insignia through the crust on the transmitter’s side panel. A circle stamped into metal. A mountain or perhaps a white peak over dark water, and beneath it letters half hidden under limescale.

She went closer.

“Elin.”

“I know.”

“No, look.”

Elin came up on Mara’s right, careful with her footing. Signe circled left, eyes on the chamber edges instead of the machine, tracking shadow gaps and side passages. Good. Someone had to.

Mara wiped her glove against the panel. Mineral flaked off in thin scales. More of the stamp showed. T.V.E., wrapped around a small pennant and the date 1938.

Signe saw it and swore softly. “That’s the prefix.”

“Not the radio prefix,” Elin said. “The expedition mark.”

“How do you know?”

Elin pointed with the flare pistol toward the canvas on the wall. Faded paint showed there too: the same circle, same pennant, ghosting through mildew. “Because they put it on everything.”

Mara crouched beside the machine. The housing had once been painted navy or black. The color had gone to scab and bloom. One access panel hung ajar by one hinge. Inside, coils and vacuum tubes sat in nests of mineral growth and calcified dripstone. Some tubes had burst long ago. Others remained intact under a rind of dust. A copper line disappeared into the stone floor where black glaze had built up around it, as if hot water rich with minerals had run there for years.

“It should be dead,” Mara said.

“It is dead,” Elin said. “Or it should have been thirty times already.”

The three ticks sounded in the headset. Louder. Clean enough now that she could hear a faint hum behind them, a power-note barely holding.

Mara followed the wire from the transmitter to a second box mounted on the stone shelf. This one had a hand crank on the side and a gauge under clouded glass. The gauge needle trembled just above zero.

“Don’t,” Elin said, reading her before she reached.

“I’m looking.”

“You’re about half a sentence from touching.”

Mara didn’t answer. Her eyes were on the floor behind the machine. There, tucked between the rusted base and the wall, was a leather case swollen by damp and filmed with white mold. Beside it lay a notebook with its spine gone, pages splayed and fused in places by mineral deposits.

Signe saw it too. “That I’m taking.”

Elin exhaled. “Use the sample sleeve.”

Signe unhooked a clear specimen bag from her harness, slid the notebook into it with two fingers, and carried it back to a drier ledge. The pages were swollen, edges browned and feathered. The cover might once have been green cloth. Now it was nearly black.

Mara kept staring at the machine.

The transmitter’s key sat under a fringe of white growth. Brass, blackened with age. The key lever trembled the slightest fraction with each tick. Not enough for the eye at first. Enough once she saw it.

“Tell me you see that.”

Elin bent. Her face tightened. “Maybe vibration.”

“From what?”

Signe had peeled open the first pages of the logbook inside the sample sleeve. Several tore free and slumped across the plastic in wet leaves. She turned until she found a page that held.

“There’s a name,” she said. “Thomas Vale.”

The cavern took that in and gave back the last name from somewhere far along the ice, altered and hollow.

Mara looked over. “Read.”

Signe lifted the page toward the glow. Her voice lost its usual dry edge without her meaning it to.

“January twenty-third. Air in lower chamber measured at sixty-one degrees Fahrenheit by pocket thermometer. Water running under eastern shelf. Moss or algal matter self-luminous in dark conditions. Finch insists we have found a volcanic intrusion. I do not agree. Fauna observed at eleven-thirty p.m.—white, six-limbed, herd behavior, no visible fear of lamp flame.”

She stopped. Swallowed.

“Keep going,” Elin said.

Signe turned another clotted page with painful care. “January twenty-fifth. Wireless set performs better below than at surface camp despite damage sustained in lowering. Signal return irregular. Palmer says the ice overhead may act as a lens. Hates that explanation even while offering it.”

Mara almost smiled at that. Almost.

The next page was worse, stained brown at one corner, but legible in the center.

“January twenty-seventh. We have extended line into the black corridor beyond the warm basins. The men refuse to pass between the two stone posts after Haines’s account. He claims the air there showed another room where ours should be, with our own lamps in wrong places and men moving in dress not our own. I reprimanded him for nerves. Tonight I saw it myself.”

No one moved.

The hum under the ticks seemed louder now, though that might only have been attention.

“Elin,” Mara said.

“I heard.”

Signe looked up from the book. “Another room.”

“A trick of light,” Elin said at once. Too fast.

Signe’s mouth tightened. “In a cave under Antarctica. But the impossible radio is where you draw the line.”

“I draw it where a dead man’s journal tries to start steering us.”

Mara had stopped listening to them. On the transmitter’s side, beneath a curtain of mineral scale, something had flashed once—brief amber behind a cloudy tube.

Not a reflection. Internal.

She reached toward the open panel.

Elin’s hand caught her wrist hard. “No.”

“It just lit.”

“Then it can do it again without you.”

“Or it can’t.”

Their faces were close enough now that Mara could see the salt track dried at Elin’s temple where sweat had run under her cap. She also saw the fear there, pared thin and sharp. Not fear of the machine. Fear of losing control of one more variable.

Signe said, quietly, “Let her look.”

Elin didn’t release Mara at once. Then she did, suddenly enough that Mara’s hand dropped the last inch on its own.

“Three seconds,” Elin said. “Then you tell me what you think before you touch anything else.”

Mara nodded.

She brushed the growth aside with the insulated knuckle of her glove. It broke with a brittle snap and gave off a stale, medicinal smell. The tube beneath was warm.

She froze, then pressed lightly again.

Warm.

Not cave-warm. Component-warm. The kind of living heat electronics made when current ran where it had no business running after eighty years under ice.

“There’s power,” she said.

Elin gave a short, humorless laugh. “Of course there is.”

Mara leaned farther into the panel gap. Coils. Corroded contacts. A relay armature with rust on the pivot. And threaded through all of it, impossible as roots in a watch, were fine white filaments from the cavern growth, laid over metal junctions, vanishing into screw heads and wrapped around wire breaks as neatly as solder.

The fluorescent life from the tunnel had gotten in here.

More than gotten in. Bridged.

“Signe,” Mara said, still staring. “Your sample sleeve light.”

Signe handed over the chem lamp stub. Mara cracked it wider and held its blue spill close to the open chassis.

The filaments answered.

They brightened from dead white to pearl-green, and the gauge needle on the adjacent crank box twitched upward.

All three sisters went still.

“Again,” Mara said.

Signe shaded the light with her hand, reducing the glow. The needle sank. She uncovered it. The needle rose.

Elin made a small sound in her throat that was not surprise so much as reluctant recognition, one puzzle piece taking hold of another.

“The plants,” she said. “Not plants. Whatever they are. They’re part of the circuit.”

“Or feeding it,” Mara said.

“Or being fed by it.”

Signe turned back to the logbook, flipping pages faster now. “Listen. Here. February third. Growth about the set has advanced. Finch cut it back from the contact points and transmission ceased entirely until strands resumed. We are keeping a ring cleared for fear of fire, though Palmer argues the substance transmits charge better than copper where damp.”

Mara looked up sharply. “There.”

Signe found another line lower on the page. “Vale underlined this.” She squinted. “‘It is no relic if it answers.’”

The receiver in Mara’s hand spat a burst of static so loud they all flinched.

Then a voice, thin as paper and scraped raw by distance, spoke directly into the chamber.

“—hear me now?”

Silence hit after it like a dropped curtain.

Mara’s pulse slammed against her ribs. She brought the headset to one ear, then thrust the free side toward Elin. “Did you get that?”

Elin had gone pale under windburn. “Yes.”

Signe was already at the logbook again, pages shaking in her fingers now for a different reason. “Find the date,” Mara said.

“I’m trying.”

The transmitter key clicked once by itself.

Not fully down. Just a tiny metallic tap.

Elin raised the flare pistol without seeming to know she had done it. “Who’s there?”

The words sounded absurd in the cavern. The machine answered with static and three measured ticks.

Mara looked at the controls on the side panel: a tuning dial seized with crust, a smaller gain knob still free enough to move under two fingers, a knife switch black with age. Labels stamped in old enamel: FIL, PLATE, ANT.

She knew these layouts. Not this model, not this era in the hand, but enough to read the bones of it. The hum was too weak. The filament circuit was starving, somehow kept alive by the growth and whatever current the chamber bled through the box. If she changed the wrong thing, she could kill it.

If she changed nothing, the voice might vanish anyway.

“Elin.”

“No.”

“You don’t know what I’m asking.”

“I know enough.”

Mara turned and met her sister’s stare. “The signal found us. It led us through half this buried place. You think that was an accident?”

Elin’s grip tightened on the pistol. Her knuckles whitened. “I think accidents stack up when people start needing meaning.”

Signe did not look up from the book. “February eighth,” she said. “Vale writes, ‘It repeats only when attended. Long intervals of noise otherwise. When we answer, the man answers. When we leave the set alone, he weakens or goes.’”

No one spoke.

The water dripped somewhere in the dark. A fungus blister popped softly on the wall beside Mara’s shoulder.

“When we answer,” Mara said.

Elin looked from Mara to the transmitter, then past it to the two iron uprights driven into the stone shelf. In the blue pulse they looked less like supports than markers. Gateposts. Deliberate. Between them the air had a faint wavering in it, no more than heat above a road. Easy to miss unless you were already looking elsewhere and caught it at the edge.

She saw Mara see it.

“Don’t,” Elin said.

“I wasn’t moving.”

“Good.”

Mara set the receiver on the shelf, slipped off one glove with her teeth, and put two bare fingers on the gain knob.

Elin swore under her breath. “You promised three seconds.”

“That was before the ghost started talking.”

“Mara—”

She turned the knob a hair.

The effect was immediate.

The white filaments inside the chassis flared green. The gauge needle jumped. Somewhere inside the box a relay snapped over with a dry, precise click that had not been heard in this cavern since wool and canvas and paraffin light. Static rose to a scream, broke apart, and resolved into breathing.

Human breathing.

Then a man’s voice, close enough now to hear the exhaustion in it, the clipped schooling under it, the effort being made not to sound afraid.

“Yes,” he said. “That’s better. Don’t shut it down again.”

All three sisters stared at the transmitter.

The key went down once under its own power.

A waiting finger answered from the other side.

Mara did not take her hand off the knob.

“Who are you?” she said.

A wash of carrier hiss answered first, the kind with grain in it, old and dry, and under that the breath again. Not performance now. A man trying not to cough.

There was a pause long enough for Elin to shift her stance and bring the flare pistol level with the space between the iron uprights.

Then: “Vale. Thomas Vale.” The voice sharpened and thinned, as if the speaker had turned his head. “Who in God’s name is this?”

Signe made a small sound through her teeth. Not fear. Recognition.

Mara said, “My name is Mara Orlov. You’ve been transmitting on an expedition call sign registered in nineteen thirty-eight.”

The chamber seemed to listen with them. Water clicked into water somewhere in the dark. The growth crusted over the transmitter’s casing gave off a low bottle-green glow that brightened with each three-tick pulse.

On the shelf beside the set, the logbook lay open, its swollen pages wrinkled like wet skin.

“Say that again,” Vale said.

Elin took one step closer, boots grinding salt-white mineral grit. “What is today’s date?”

“You first.”

“Answer the question.”

“No.”

His refusal came too fast to be brave. It had the shape of a man already frightened and trying to keep one hand on procedure because the rest of the room was slipping.

Mara looked beyond the machine. Between the two iron uprights the wavering in the air was stronger now. Before, it had been easy to dismiss: a trick of heat over rock, the shimmer you got above exhaust, over summer pavement. Here it hung in cold blue cavern light, a vertical bruise in the empty space, no wider than a door and maybe seven feet high. The edges were not edges at all. They breathed. Stone seen through it bent slightly, as if under water.

“Do you see that?” Signe whispered.

Nobody answered her because all three of them had already leaned their eyes there.

Within the wavering, the black stone behind seemed to pale, then darken, then pale again. For half a heartbeat Mara thought she saw canvas. A ridge line, tan and angular, gone before her brain could trust it. Then the rough shelf behind the seam returned, overgrown and blue-lit and slick with mineral tears.

Elin saw it too. She took the flare pistol off the empty air and lowered it toward the floor, not because she felt safer but because the thing between the uprights did not look like anything a flare could threaten.

“What date?” Vale said again, but now his voice was smaller. Distracted. As if something in his own room had changed.

Mara wet her lips. “February ninth,” she said, and gave the year.

Static cracked so hard it slapped the chamber.

“No,” Vale said.

His voice had moved—still through the transmitter, but farther back from it now. “No. No, that is nonsense.”

Signe had gone pale under the smear of dirt and meltwater on her face. She stepped to the shelf, bent over the set, and listened with one ear almost against the speaker grille, as if proximity could clean the impossible into sense.

“Elin,” Mara said quietly. “Look.”

The shimmer deepened.

This time there was no mistaking it. The stone shelf beyond the uprights was visible and not visible at once. The clotted ropes of luminescent growth that presently bridged the transmitter’s contacts were absent. In their place stood a cleaner machine, bright at the corners where old varnish and brass caught a warmer light than existed anywhere in the buried cavern now. A hurricane lamp burned on a crate. Canvas walls—no, not walls. Tent flaps rigged against stone. A camp built hard against the shelf itself.

Then it blinked out and the present slammed back in.

Elin’s face had gone set and flat, the look she wore when panic had knocked and been turned away by force.

“Hallucination from heat,” she said.

“Then we’re all having the same one,” Signe said.

“Or fumes. Fungal spores. Something the growth is throwing off.”

Mara gave her a look. “You believe that?”

“I believe I can’t afford not to test the ordinary first.”

That was Elin all over: not faith in ordinary things, exactly, but loyalty. She would keep offering them explanations long after they stopped fitting because once you surrendered that habit, the dark got too much room.

Vale’s voice came through the machine again, more distant still. “Palmer? Finch? Are you touching the lamp?”

A scrape followed, tin on stone, and then another voice in the transmitter—fainter, younger—unintelligible except for the urgency in it.

Signe’s head snapped up. “There’s more than one.”

Mara stared at the shimmer between the uprights. “He’s not talking to us now.”

“No,” Signe said. “He’s talking to his own room.”

Elin crouched and unhooked the ice hammer from the side of her pack. The steel head was dented from the tunnel wall where she had used it to trick the predator. She weighed it once in her palm, eyes on the seam.

“What are you doing?” Mara said.

“Finding out whether that’s light or structure.”

She straightened before either of her sisters could stop her and tossed the hammer underhand through the space between the uprights.

It did not strike stone.

For an instant it was there, handle-first into the shimmer, the metal warped and doubled like a spoon seen through moving water. Then the whole tool slid forward and was gone.

Not dropped. Not hidden. Gone.

From the transmitter came a violent clatter.

“Christ!” a man shouted.

A second voice barked something over him. The words were blurred by static, but fear carries cleanly. Signe flinched as if the sound had touched her skin.

The seam swelled bright. In it, the cleaner shelf flickered back into view, and this time the ice hammer lay on the ground beside a canvas camp stool. Solid. Real. Impossible.

Elin’s fingers opened and shut once, empty now. She looked at her hand like it had betrayed her.

Mara felt the cold along her spine despite the warm draft bleeding out of the stone. “You saw that.”

“I threw it,” Elin said. Her voice had gone hushed and hard. “I know what I threw.”

In the shimmer, a boot stepped into view. Heavy wool puttees, leather darkened by melt, hobnails bright in the lamplight. The figure attached to it came only halfway into the distortion before the image tore and smeared. Then there was only bent air and the blue pulse of the growth again.

Signe grabbed the headset receiver from the shelf and jammed one earpiece against her head. She thrust the other at Mara. “Listen.”

Mara took it.

The receiver’s hum was stronger than before, almost musical now, a thin overtone braided through the static. Under it, close enough to raise the hair on Mara’s wrists, the transmitter’s three-tick pattern sounded twice. One set from the machine in front of them. Another, delayed by a fraction, from somewhere beyond.

Same rhythm. Same hand. Different rooms.

She handed the earpiece to Elin.

Elin listened only a second before jerking it away. “Again.”

Mara pressed it back to her ear. There—three ticks, then the answering three from farther off, softened as if by canvas and open air. Not an echo. The lag was wrong. Too neat.

Signe was already turning pages in the logbook with shaking fingers. “Vale wrote about another room. Lamps. Men dressed wrong. He thought he was seeing us.”

Mara looked through the seam again. “Maybe he was.”

The shimmer rolled from top to bottom like heat struck by wind. The current of warm air around the uprights strengthened, carrying with it the smells that had been buried under mineral damp and old machine oil: singed wick, wet wool, a trace of tobacco so stale it was almost sweet. Not memory. Present, somehow. Present from elsewhere.

“Elin,” Mara said, “if this is interacting with the radio—”

“Don’t.”

“It already is.”

“I said don’t.”

Meaning: don’t say the thing aloud and make it harder to deny. Don’t build rules out of glimpses. Don’t let wonder outrun caution.

Mara turned back to the set. The gain knob sat under her fingertips with a dangerous softness to it, easy to move, easier to move too far. The gauge needle quivered in the green-lit arc. Filament current, plate current—starving but alive, fed by the strange conductive growth and whatever field lived in the seam. She did not understand the whole circuit. She understood enough to know it was balanced on a knife edge.

“How long can we hold it?” Signe asked.

Mara listened to the note in the machine. “Not long if it climbs any hotter.”

“What happens if it drops?”

“Maybe nothing. Maybe it goes dark.”

“Maybe the thing between those posts goes dark too,” Elin said.

No one contradicted her.

The transmitter key moved again under no visible hand. Three measured taps. Vale, somewhere on the other side, sending blind into a future he did not believe.

Mara leaned toward the grille. “Vale. Listen carefully. We need you to tell us what you see between the iron posts.”

At once the breathing returned. He had come back to the microphone fast, as if he had not wanted to leave it in the first place.

“I see—” He broke off. “Good God.”

The seam flashed.

For a stretched, terrible second both rooms occupied the same space cleanly enough to hurt.

No overgrowth. No mineral curtains. No long years of damp accretion. On the far side stood a rough expedition station built into the cavern shelf: a folding table under maps pinned with knife blades, a pressure lamp hissing white, coils of cable, a crate stamped with the same T.V.E. mark as the logbook. The transmitter there was less buried, its brass brighter, its wooden case not yet split. Beyond it hung tenting to hold heat. Snowmelt dripped from a line into a galvanized bucket.

And in front of all that, one gloved hand on the table, stood a man.

Not old. Mid-thirties, perhaps. Beard gone to stubble. Nose sharp from cold and poor sleep. Wool parka buttoned to the throat, collar edged with frost. He stared through the seam with the fixed, appalled concentration of someone watching his own reflection move independently.

He saw them.

Mara knew it by the way his eyes snagged first on the flare pistol in Elin’s hand, then on Signe’s bareheaded silhouette, then on Mara herself by the machine—brown synthetic base layer visible where her parka hung open, bright plastic cable ties on her harness, the impossible clean colors of another age.

Vale took one involuntary step back.

On their side, Signe made a sound like a swallowed sob.

“Do not move,” Elin said, though she might have meant it to any of them, or to the air itself.

Vale’s mouth opened. His lips formed a word before the transmitter carried it.

“Women,” he said.

Not insult. Astonishment. The world rearranging under him.

Then the image shook. The seam tore sideways into strips of light and stone. Vale blurred, split, became three partial figures and none. The lamp behind him smeared to a white ribbon. A smell like hot pennies flooded the present cavern.

Mara lunged to the knob as the gauge needle jumped.

“Don’t touch it,” Elin snapped.

“It’s running away.”

“Then let it.”

“If it spikes, it burns.”

Mara made the smallest correction she dared, easing the gain back a fraction.

The machine answered with a whine that drilled her molars. Green filaments flared hard enough to throw knife-edged shadows across the shelf. The luminescent growth bridging the contacts tightened and writhed, each strand drawing thin and bright as wire under load.

In the seam, the 1938 camp snapped back for one last instant. Vale was nearer now, one hand half-raised toward them, not in greeting but in the reflexive warding gesture people make toward fire or a dropped weight.

His voice hit both ways at once—through the machine and thinly from the seam itself, as if the air had learned language.

“Stay where you are,” he said.

The phrase arrived in the cavern carrying eighty-odd years and exactly the wrong authority for any of them to obey.

Then Elin’s hammer, lying on the floor in his camp, skidded of its own accord another few inches. Perhaps kicked by someone out of view. Perhaps shaken by the surge. It struck a stool leg.

The crack of metal on wood was tiny.

It was enough.

Something moved in the dark behind Vale’s left shoulder. Not a man. Lower. Quick. A pale shape slipping along the edge of his canvas shelter where no canvas should have been safe from teeth.

Vale half-turned at the sound.

Mara saw it the same moment Signe did. “Behind you!”

Whether he heard the warning through the static or read it in her face, he started to twist—

—and the seam collapsed to a thread of silver, then nothing at all but empty space between the iron uprights and the blue pulse of the cavern growth beating like a slowed heart around the dead-silent transmitter.

Mara put her hand back on the gain knob before Elin could stop her.

“Three seconds,” Elin said.

“That’s all it’ll take.”

“Three.”

The transmitter still looked dead except for the green threads laid through it by the cavern growth, but dead things in this place had already proved dishonest. Mara eased the knob clockwise until she felt resistance change under her fingers—not metal alone, something living tightening around the shaft inside the housing.

At once the chamber answered.

The filaments drew bright. A relay chattered. Somewhere between the iron uprights the air puckered, as if a skin were being pinched from both sides. Heat touched Mara’s face. Not the suffocating basin warmth from before, but a dry furnace breath with a tang of scorched copper.

Signe was already in the headset, one cup pressed to one ear, the other hanging. “Carrier’s up. Stronger than before. There’s a second tone under it.”

“Keep calling him,” Mara said.

Elin moved to the posts, flare pistol low but ready, as if light could stop time from tearing in the wrong direction. “Vale. If you hear me, answer now.”

Static. Three ticks. A hiss like water on a stove.

Then, faint and raw, “I hear you.”

The seam came back in a narrow vertical blade between the uprights. It did not open cleanly this time. It feathered at the edges, showing strips of lamp-glow, black gaps, canvas, stone, and then the whole of the other camp jumped into place.

Vale stood bent over his set, one hand braced on the table. He had changed in the few minutes since they last saw him, though that was nonsense. A cut striped one cheek. His sleeve was torn at the cuff. Behind him a second man yanked a tent flap tight and looked over his shoulder with the pale, hunted face of someone who had run out of explanations and kept moving anyway.

“Don’t break it again,” Vale said, not bothering with astonishment now. “If the field drops altogether, I lose the circuit.”

Mara did not look away from him. “Who’s with you?”

He hesitated. A small thing. Enough to see the habit of command in it.

“Baines. Mercer’s at the rear shelf. Holt can’t stand.” His eyes flicked across them, landing on the synthetic straps, the radio, the open parkas wrong for Antarctica and wrong for any year he knew. “How many are you?”

“Three,” Elin said.

“And the date?”

She told him.

He stared as if she had recited a depth sounding from the moon. The man behind him crossed himself so quickly he probably did not know he had done it.

“Thomas Vale,” Mara said. “We found your logbook.”

That struck harder than the date. Vale’s mouth tightened. “Then you know enough to leave this place alone.”

“No,” Mara said. “We know enough not to trust the parts you stopped writing down.”

Silence sat between the posts for a beat. The machine crackled under her hand. The gauge needle trembled near the red mark and stayed there, alive, undecided.

Vale drew himself up. Whatever he had been in the expedition register—a wireless specialist, survey man, geologist—he had also plainly been the person men listened to when the floor went strange under them.

“I was attempting a long-range transmission,” he said. “That much is true. Our support vessel had not met the rendezvous. We had weather damage, a broken mast section, dwindling kerosene, and too much confidence in a cave we did not understand. We hauled the set below because the rock gave us warmth and shelter from drift. There were mineral seams, conductive runoff, growth on the walls that took a charge. I thought I could use the chamber itself to throw farther than the standard rig on the surface.”

“You fed the walls into the set,” Signe said.

“I grounded through them,” Vale snapped, then checked himself. “Yes.”

“And opened this,” Mara said.

His jaw moved once. “Not at first. At first it was only range. Better signal, less loss. Then voices on dead bands. Repetition. Echoes that answered before I keyed. Men hearing themselves from half a minute ahead. We should have stopped there.”

Baines, behind him, said, “Told him so.”

Vale ignored it with the economy of long practice. “When the seam first showed, it was no wider than a ribbon. Light where there should have been none. A shelf beyond ours. We took it for some electrical delirium and then for reflection and then, when we tested it, for neither. Matter passed. Sound passed. Not always. Not safely. But enough.”

Elin kept her eyes on him. “You kept increasing power.”

“We had men to keep alive.”

The answer came too fast, and because it came fast Mara believed it.

Signe shifted closer to the logbook where it lay open on a dry patch of stone. Pages swollen, corners furred with age, pencil gone gray. She put one finger on a line without touching the writing itself. “January twenty-seventh. ‘The room again. Lamps. My own hand answering me from a place not this place.’ Then nothing for nearly a day. Then January twenty-eighth: ‘Attempted closure. Pressure event. Ross lost.’”

Vale went very still.

Mara looked up. “Ross was one of yours.”

His face changed by fractions only. The muscles beside his mouth hardened. “Yes.”

“You left that out when you told us not to shut it down.”

“I left out many things.”

“Convenient.”

His temper flashed for the first time. “You stand there with warm cloth and impossible apparatus and accuse me of convenience?”

Elin took one step nearer the seam. “Then stop rationing the truth.”

For a moment Mara thought he might cut the contact himself, knock the microphone aside, let the field go. Instead he looked past them into their cavern, into the overgrown shelf where his own camp would someday rot, and seemed to understand something that altered the calculation.

“When we attempted to close it,” he said, more quietly, “the chamber came down.”

Baines made an ugly sound in his throat. Mercer, somewhere out of sight, coughed and coughed.

Vale went on. “Not at once. That would have been mercy. The field narrowed. The warmth dropped. Then the roof started talking to itself. Cracks running where no cracks had been. Ice from above. Stone from behind. We lost Ross under a shelf collapse before we could drag him free. After that I did not try to close it again.”

Mara looked at the logbook, then at the iron posts, then at the green filaments threading the transmitter like capillaries. “But you still think closure is the answer.”

“I think if I do nothing, the thing enlarges or shifts and takes the rest of us by inches. We’ve had animals come through. We’ve had air change in the camp while the lamps burned blue. Holt says he hears voices when no one speaks. I will not leave my men in that.”

Signe lowered the headset. “And if closing it buries them?”

Vale said nothing.

The answer was there anyway.

A drop struck Mara’s wrist. Warm. She looked up.

Water had started to fall from a seam in the black rock overhead, not in the thin patient trickles they’d been following through the tunnels but in a quicker silver thread. Another drop hit the transmitter case and steamed faintly on the warmed brass.

Elin saw it too. “Mara.”

“I know.”

The green growth along the shelf had brightened. Not just around the machine. Out in the chamber as well, through the mats on the wall and the translucent bulbs hanging farther down the tunnel mouth. Their pulse had sped up until it nearly matched the relay chatter.

Signe turned toward the passage. Beyond it, from some distance away, came the soft drumbeat of many light feet.

“The grazers,” she said.

“Coming in?” Elin asked.

“No.” Signe listened. “Circling.”

As if called.

Mara bent over the logbook, flipping carefully through the damp pages with the back of one gloved knuckle. Vale’s hand had grown harder to read where the pencil had bitten through softened paper. Dates, weather notes, inventories, then shorter lines. Sleep poor. Heat increasing. Surface route unstable. Impossible wireless responsive under attendance. Then, later, jagged entries written under strain.

She found it because the page had nearly torn at the fold.

Field narrowed at 13:10. Wall-light failed in west run. Water ceased in lower crack within two minutes. Creatures in herd striking floor and retreating. Ross said it was as if one had stoppered the earth.

Mara read it again.

“What?” Elin said.

She did not answer immediately. She was looking up now, not at Vale but at the chamber itself. At the vines furred across the iron upright bases. At the mineral banding where warm runoff had fed them for years. At the open dark of the tunnel the sisters had come through, where every glowing thing had answered the signal like a nervous system spread through stone.

“Signe,” she said. “The basin chamber. When the seam flared strongest, what happened to the water?”

“It rose.” Signe looked toward her, caught up. “Not much. Enough to show on the rock.”

“And when it collapsed?”

“It dropped back.”

Elin understood a second before Vale did. “The portal isn’t just a hole.”

“No,” Mara said. “It’s a pump.”

Vale’s expression shuttered. “Explain yourself.”

Mara set the logbook down and spoke to him as if they had no time left for pride, which was true. “Your closure attempt didn’t just fail because the roof was unstable. When the field narrowed, the western growth darkened, the lower watercourse stopped, and the animals ran. Whatever this seam does, it moves energy or heat or both through the rock. Maybe air exchange. Maybe something worse. But the system down here is built around it now.”

“Built—” He gave a short disbelieving laugh. “By whom? Ferns?”

“Not built by intention,” Elin said. “Maintained by dependence.”

Baines had stepped close enough to the seam to hear plainly now. He looked from Vale to the women across time and back again. “Sir.”

Vale did not look at him.

“Sir, if the warmth goes—”

“I know what warmth does,” Vale said.

But Mercer coughed again from the back of the 1938 camp, a wet tearing cough that belonged to bad lungs in bad cold, and everybody heard that too.

Mara went back to the machine. The needle had crept higher. She backed the gain by a hair; the seam thinned, then steadied. Cost. Always cost. Hold it open too hard and the set might cook itself. Let it droop and the field would flutter. She could feel the strain through the chassis in a fine vibration, like the transmitter had developed a pulse.

Vale saw her touch and stiffened. “What are you doing?”

“Keeping us talking.”

“At what price?”

She almost said, At yours first. Instead: “I don’t know yet.”

He took that with less offense than honesty usually earned.

Signe was crouched by the tunnel mouth now, watching the blue-lit dark. “They’re there.”

The pale grazers had assembled just beyond the edge of easy sight. She could make out the nearest three by the glow washing over their flanks: wax-colored hides, narrow skulls, the ripple of six careful limbs placing and replacing on stone. They were not feeding. They were all facing the chamber.

A smaller one stepped forward. Tapped the floor twice with a forelimb. Waited.

From deeper in the tunnel, other taps answered.

Vale heard the faint drumming through the seam and went white under the cold-burn and beard. “Those things.”

“You’ve seen them before,” Elin said.

He nodded once. “Not only them.”

As if summoned by the admission, a sound passed through the far side of his camp. Canvas twitched. Something brushed stone with a dry, sliding weight.

Baines turned sharply. “Mercer?”

“No,” came Mercer’s strained voice from out of sight. “Not me.”

Everyone listened.

In the sisters’ cavern the grazers held their ground, unblinking. One of the hanging bulbs overhead dimmed, then brightened, then dimmed again. The warmth in the room shifted across Mara’s skin in alternating drafts, hot-cool-hot, as if some vast breathing had begun behind the walls.

Vale spoke without taking his eyes off whatever moved beyond his canvas. “If the seam remains, they come through. We’ve had small ones and one not small. Ross did not die only by falling stone.”

The words landed flat and hard.

Elin said, “If the seam closes, your roof may come down. If it stays open, both sides draw attention.”

“Yes.”

“That’s your choice?”

“It appears to be yours as well.”

Mara stared at the line in the logbook again: as if one had stoppered the earth.

The hidden world under the ice was no closed pocket preserved by accident. It was being fed. Warmth, water, perhaps the very chemical gradient the growth used to shine and conduct—coming in pulses whenever the seam lived. Shut it, and the basin above might freeze solid, the plants blacken, the channels go still. The herd in the tunnels, the predators riding vibration, everything balanced on this wound between years.

And if they kept it?

Then the wound remained open. Creatures crossed. Time bled. Men in 1938 stayed pinned to a decision none of them had yet made.

Signe rose slowly from her crouch. “Mara.”

Mara looked up.

Signe pointed, not into the tunnel but at the floor beside the transmitter shelf.

A new crack had appeared in the stone there. Not wide. A pencil line. But warm vapor came up through it in faint white threads, and with each pulse of the seam the crack opened the width of a fingernail, then eased back. Breathing with the field.

On the far side, beyond Vale, somebody shouted. Baines spun and lunged out of frame. Canvas crashed over. There was the bang of a crate kicked aside and then a human cry cut off as if a hand had been clapped over the mouth.

Vale snatched for something on his table—an ice axe, Mara realized too late—and faced the dark beyond his shelter.

“Elin,” Mara said.

“I know.”

“Tell me not to do it.”

Elin did not. She was watching the seam, calculating distances that should not have existed, weighing three lives beside three others beside whatever lived below all of them. Her knuckles were white around the flare pistol grip.

Vale, half-turned toward danger in his own year, shouted back over his shoulder without looking at them. “If you can hold it, hold it. Do you hear me? Hold—”

Something hit the far side of the canvas hard enough to bow it inward like a lung taking breath.

The pale hide showed through for an instant.

Not the grazers.

Longer. Lower. A head shape sliding under the fabric with terrible patience.

In the sisters’ cavern, every hanging bulb flared at once, brilliant blue-white, and the crack in the floor gave a sharp little report like a knuckle breaking.

Mara gripped the gain knob.

The seam jumped wider.

The widened seam made a noise like wet cloth tearing, though nothing visible split. Air rushed through the iron uprights and struck Mara full in the face—lamp oil, old wool, hot metal, a man’s sweat that had crossed eighty-eight years in less than a breath.

On Vale’s side, the canvas bulge flattened and then burst inward.

The creature came through low, all shoulders and spine, hide the color of dirty tallow stretched slick over muscle. It did not leap. It poured. One moment it was under the tent wall, the next it had unfolded across the floorboards and crates with that same obscene smoothness the first predator had shown in the tunnel, only larger, scar-latticed along the ribs, with a jaw that flexed sideways before opening.

Vale swung the ice axe.

The pick bit behind the thing’s skull and skated off. The blow turned its head, no more.

“Elin,” Mara said.

“I see it.”

Elin fired through the seam.

The flare crossed in a bar of white fire and struck the camp table, kicking maps and a tin mug into the air. Vale ducked. Baines shouted. The predator recoiled from the blast, not from pain but from the impact and the heat, and that told Mara enough. Same rule. Vibration first. A hard strike could pull it.

Then something moved at her left.

Signe had already dropped to one knee at the transmitter shelf, gloved hands wrapped around the crank box. “Tell me if this matters.”

“It matters,” Mara snapped.

“Everything here matters.”

The machine had changed under the wider field. Green filaments that had lain flat in the seams of the casing now stood up like wet hair. A relay chattered too fast. Beneath the stone shelf the warm crack opened and shut with tiny snapping sounds, exhaling mineral steam.

Another tap sounded from the tunnel mouth.

Then a rush of answering taps, nearer, faster, layered over one another until the chamber seemed to have a second heartbeat.

The grazers came in a pale line, six-limbed bodies angled low, eyes catching the hanging bulbs in pearl-blue flashes. They did not charge the humans. They spread along the edge of the room in a crescent, keeping the tunnel at their backs, forelimbs lifting and placing in unnerving unison.

Mara did not have time to decide whether that was good.

A second predator broke from the dark behind them.

It drove through the grazer line and scattered bodies in every direction. One of the smaller animals went down screaming in a dry flute note Mara had not heard before. The predator never paused to bite. It slapped the creature aside and kept coming, head low, jaw working, drawn by the transmitter’s chatter and the seam’s hot pulse.

“Right side!” Signe yelled.

Mara snatched up the flare rifle from where it had been leaned against the shelf. Her forearm screamed when she lifted it—the bruised arm the first predator had hit—but the barrel came up anyway. She fired at the floor two meters in front of the thing.

The flare hit stone and skidded under its chest. White magnesium blew the chamber wide open. Every frond, bulb, mineral runnel and hanging rib of ice sprang out in hard-edged light. The predator twisted away from the burst, claws scoring sparks. It struck not for Mara but for the flare’s ricochet, smashing into the rock wall where the hot slug had bounced.

Elin was moving already, dragging a broken packing crate toward the gap between the shelf and the nearest upright. “Do not let them get behind the machine.”

“As if I planned to,” Mara said.

Across the seam, Vale had found his footing. He kicked the overturned table at the larger predator and shouted something sharp to Baines. Baines hurled a paraffin lantern. It shattered against the creature’s shoulder, flame running over hide and canvas alike. For one splendid second it looked vulnerable—burning, visible, fully animal.

Then it rammed through the fire.

Mercer appeared at the edge of the far camp with a rifle older than all of them. He shot once. The report cracked across both rooms. The bullet must have hit stone or iron, because the predator snapped not toward the shooter but toward the impact, lunging at a tent pole that had jumped with the strike. It tore through canvas and wood while Vale buried the axe in its flank up to the eye.

“Keep making it choose wrong,” Elin said.

A grazer slammed into Mara’s thigh.

Not attacking. Passing. The animal brushed her hard enough to stagger her, then cut across the chamber and stamped twice beside a boulder near the tunnel mouth. Another answered from the opposite side. A third, one with a torn ear-web, darted in and struck the stone trough with both forelimbs in a drumbeat.

The predator in their chamber wheeled toward that noise.

Mara saw it then. The crescent. The spacing. Not random, never random.

“They’re baiting it,” she said.

Signe looked up from the machine, face slick with sweat. “Good for them.”

The grazers broke and re-formed with impossible speed, each quick tap or body check pulling the predator a little farther from the transmitter shelf, a little deeper into bad footing where meltwater glazed the stone. One false movement from Mara and they would have bolted from her too. Instead she lowered the rifle half an inch and held.

The predator took the offered lane and sprang.

Three grazers dropped flat. A fourth darted under its chest. The animal landed wrong, foreclaws scraping on wet mineral, and slammed shoulder-first into the basin lip. Elin crossed the space in four strides and drove the pick end of her ice hammer into the side of its skull.

The blow did not kill it. It stunned. Enough.

“Now!” Elin shouted.

Mara fired her second flare straight into the opened jaw.

The blast lit the throat from within. For an instant she saw nested rows of teeth set on hinging plates, pink-white and slick as shell. Then the flare punched deeper and burst. The predator thrashed once, smashing its tail against the shelf hard enough to ring the transmitter casing, then collapsed in a steaming fold.

That ringing changed the machine’s voice.

The relay stumbled. A high whine came from somewhere behind the gain housing, fine as a dentist’s drill. Green light raced along the growth bridging the terminals. Signe swore and slapped her mittened palm over a brass cylinder the size of a thermos lashed to the side of the set.

“This was loose already,” she said. “It’s looser now.”

Mara spared half a glance. The cylinder was one of the regulators: a ribbed brass canister with mica windows and a needle trembling inside cloudy glass. Hairline cracks ran from one mounting bracket where the predator’s tail had struck.

On the far side, the larger predator had Vale against the shelf.

It had him by the coat, not the body, and was shaking him in short brutal snaps that slammed his head against stone. Baines hit it with a shovel. Mercer fired again and missed wide, the shot punching through a lamp. Kerosene flamed down the canvas wall in a bright sheet.

“The seam,” Elin said.

Mara knew before she said it. Wider now than a doorway. Wide enough for a man. Wide enough for that thing to come all the way through if it turned. Wide enough for them to cross.

Signe was already shaking her head. “No.”

“Agreed,” Elin said.

“That wasn’t a suggestion,” Signe snapped. “Look at the shelf.”

Mara looked.

The crack beneath the transmitter had widened from a pencil line to a black slit. Warm vapor breathed out in gusts that smelled of iron and rotten eggs. Each pulse of the seam made the stone lip flex. Not much. Enough.

Another sound rolled up the tunnel. Not taps this time. A slick body on stone. Then another.

More predators.

The grazers heard them too. The pale line at the room’s edge trembled and tightened. The torn-ear animal turned its head toward Mara, one milky eye fixed on her face. It stamped once, hard, and backed toward the shelf instead of away from it.

“Why are they coming closer?” Signe said.

“Because the tunnel behind them is worse,” Elin said.

The next predator came at speed, a lean juvenile by the look of it, narrower chest, quicker stride. It did not commit to the chamber floor at once. It climbed the wall growth in two effortless bounds, claws finding purchase where there should have been none, and skimmed along the ice skin above them.

Mara swung up the rifle but knew she was late.

The grazer with the torn ear launched first.

All six limbs hit the wall predator at once. Another joined it. Then two more. Not fighters, not really; too slight, too soft in the belly. But they hit with enough combined force to spoil the leap. Predator and grazers came down together in a knot of limbs, all of them shrilling.

Elin fired the flare pistol into the pile’s far edge, not the center.

The blast made the juvenile snap toward open ground. That open ground was the stone trough. Mara had one round left in the rifle. She waited until the animal gathered itself, until the body compressed and the next impact became inevitable, then shot the trough lip.

Stone exploded. Water and light went up together. The predator veered into it by reflex and shattered its own foreleg against the basin rim with a crack Mara felt in her teeth.

Signe seized a length of cable from the camp debris and flung it. It landed across the broken leg and trailing hind limbs. Elin planted a boot on the line and hauled. Mara dropped the rifle, grabbed with her good hand, and together they dragged the thrashing animal sideways into the steaming crack by the shelf.

For one absurd instant nothing happened.

Then the stone gave.

The crack yawned to the width of a trapdoor. Hot white vapor burst out under pressure. The juvenile predator vanished to the hips, clawing at the shelf edge. Its tail beat against the regulator canister with a series of gonging blows. One mica window starred. The needle inside pinned hard right.

“Let go,” Signe shouted.

They let go.

The stone lip collapsed under the animal’s weight and it went down into brightness with a fading scrape of claws.

The chamber shook.

Not enough to drop the roof. Enough to set every hanging bulb swinging and make the seam shiver between the uprights like heat over an engine block. On Vale’s side, the larger predator flinched at the vibration, loosened its grip, and Vale tore free. He stumbled backward, beard and collar smoking from the lantern fire, then saw the open seam and made the kind of decision people later called brave because there was no use naming it otherwise.

He ran at the threshold with the axe in both hands.

“Vale, no!” Mara shouted.

Too late.

He crossed through in a flare of green light and struck the predator from the side as it turned toward the opening. The axe buried deep. Momentum carried both of them halfway across the seam into the sisters’ chamber, where the field caught and dragged at their outlines, stuttering them for a fraction of a second between rooms.

Mara never forgot that sight after—Vale doubled, blurred, one body wearing two times of dirt.

Then the seam released him. He hit modern stone hard on one knee. The predator came with him, shoulder and head first, bigger than it had looked in camp, one foreclaw already raking for purchase near the transmitter shelf.

“Down!” Elin barked.

Baines, still on the far side, understood before anyone else. He seized the iron camp table and rammed it through the seam like a battering ram.

The legs caught the predator broadside. The beast slammed into the upright with a clang that boomed through the cavern. One iron post shifted at its base.

Everybody heard that.

Nobody liked it.

Vale ripped the axe free and chopped again, not at the head this time but at the forelimb joint. Bone gave with a dull, green-stick snap. The predator screamed—a deep ripping sound, almost mechanical—and twisted toward him.

A grazer darted under its chest and struck the bad leg.

Another hit from behind.

Then six, maybe seven of them were there, pale bodies hurling themselves in and away, never staying long enough to be seized. They were not trying to kill it. They were doing what their kind had done at the trough, what they had tried to show with taps and spacing and opened lanes. Turn it. Mislead it. Feed it the wrong impacts until the dangerous thing spent itself against stone.

Mara caught the pattern and moved with it.

She snatched the steel sample case from beside the shelf and hurled it left. The predator snapped at the clang. Elin hit the opposite upright with the flat of her hammer. The beast pivoted again. Vale drove the axe into its neck. Baines, from 1938, shoved a crate through the seam that burst apart under the animal’s hindquarters. Signe, white-faced and furious, grabbed the loosened brass regulator canister with both mitts and ripped it free from its shattered bracket.

“Signe!”

“It’s venting!”

As if to prove her right, green sparks spat from the regulator socket. The transmitter’s note dropped from whine to a chest-deep hum that shuddered up through the soles of Mara’s boots. The seam narrowed by an inch. Then widened by two.

The predator reared.

Not from pain. From the machine.

Its blind attention locked to that brutal hum the way a compass locks north.

“It’ll go for the set,” Mara said.

“Then move it,” Signe said, and hurled the regulator.

The brass canister arced spinning across the chamber, struck the black stone near the tunnel mouth, and burst in a spray of mica and blue-white sparks.

The predator launched after it.

It landed where the grazers had already begun to peel away. Its momentum carried it over the broken edge of the steam crack. One hind leg found nothing. The body twisted, claws raking for purchase. Vale stepped in once, compact and merciless, and buried the axe handle-deep between shoulder blades.

The weight tipped forward.

This time the stone took it whole.

The collapse was not large. A collapse did not need to be large. The floor under the transmitter shelf dropped half a handspan with a popping series of fractures. One iron upright canted inward. The seam pinched down to a knife-cut of light, flared so bright Mara had to turn her face, then opened again jaggedly, no longer clean between the posts but ragged at the edges, shedding threads of green fire into the air.

Mercer shouted from the far side. Baines shouted something back. Vale did not move from where he stood over the new hole, chest heaving, one boot half over the crack, looking at Mara as if he had crossed not a threshold but a sentence.

Signe was at the transmitter before the echo had died. She leaned in, listened, then put two fingers against the gain housing and snatched them back.

“Too hot,” she said. “The left regulator’s gone and the right is drifting. Mara, if you touch that knob again, I think it cooks through.”

Elin came to stand beside them, breathing hard, hair plastered to her temple with sweat. Blood darkened one sleeve; not hers, Mara thought, then saw the shallow rake across her glove and revised that. Nearby, one of the grazers lay on its side, flanks fluttering, while another nosed at its neck with quiet, baffled patience.

Beyond them the tunnel was not empty.

More blue pulses moved there. More shapes. The surviving grazers had re-formed at the mouth, but their line was thin now, broken in two places.

On the far side of the seam, flame had climbed half of Vale’s canvas wall. Mercer was beating it with a blanket. Baines had found another lamp and was trying to keep it upright on a shelf that no longer stood level. Their room looked less like a camp now than a photograph left too near a stove.

Vale wiped his mouth with the back of his hand. There was blood on the beard, fresh and dark. “Can you still hold it?”

Signe answered before Mara could. “Not like this.”

Mara crouched and looked into the regulator socket. Inside, the contacts had gone soft and black at the tips. The green filaments bridging them still lived, still pulsed, but they were blistering. One more hard surge and they might weld. Or burn away. Either would choose for them.

Behind her, from the tunnel, came a new sound: not tapping, not the slide of a hunting body, but a slow communal clatter like many small teeth struck together.

Elin turned toward it and raised the flare pistol, though only one shot remained.

“No one touches the gain,” she said.

Vale looked at the narrowing wild seam, then at the fire behind him, then at the chamber where dead predators steamed beside a failing machine and pale creatures held a line they did not understand but had chosen anyway.

“Then make your choice quickly,” he said.

In the tunnel, something larger than the grazers shifted in the blue dark, and the hanging bulbs all around the chamber went suddenly, simultaneously dim.

The chamber dimmed until the blue growth on the walls looked drowned under glass.

Then cold struck Mara’s left cheek.

Not cave-cold. Surface cold. Knife-thin and dry, with the smell of snow that had never touched stone. Her right hand, braced against the transmitter shelf, felt the opposite: a wash of heat rising off the metal housing and the green filaments blistered across its open contacts. Frost feathered over the iron upright nearest her while beads of warm condensation rolled down the other.

“Elin,” she said.

“I see it.”

But Elin was looking somewhere else.

For one brief, nauseating second Mara followed her gaze and saw the chamber doubled. Not a reflection. Not a clean split like the seam had been between the posts. This was the room itself failing to decide. On one side of her sight the black rock shone wet and bare, streaming with mineral water and thick white steam. On the other it lay under a skin of rime, every ledge sugared in ice crystals. The dead predator by the steam crack was there in both versions, but in one it smoked; in the other it was rimed white, its exposed teeth furred with frost.

The image snapped. The room came back hard.

From the tunnel mouth came the clatter again, louder now. The grazers had bunched shoulder to shoulder in the blue dark, pale bodies pressed so close their six-limbed silhouettes merged. They worked their teeth together in that dry communal chatter, heads all angled inward as if listening to something under the floor.

Mercer’s voice spilled out of the seam.

Not from the far side where he stood, though Mara could see him there still beating at the smoking canvas. It came from behind her left shoulder, very near her ear.

“Don’t touch it,” he said in a thin panic.

Signe jerked so hard she struck the shelf with her hip. “He was over there.”

Mercer looked up across the seam, mouth moving a half second later. “—touch it!”

The delay folded over itself. His warning arrived twice, once too early and once too late.

Baines swore. Vale turned in place, searching for the first voice as if a man had spoken inside his camp and inside their chamber at once.

Elin took one step toward the iron posts, stopped, and set the flare pistol low instead of high. Careful. Thinking through the break in things rather than flinching from it. “No one answer anything unless you can see who said it.”

“That seems optimistic,” Signe muttered.

The hanging bulbs above the chamber woke in a stagger. Three near the tunnel glowed hot green. Two over the shelf guttered blue-white. One above Mara flashed once and went dark. Beneath that rotten light, the seam no longer held a human shape. Its edges frayed and cinched, showing scraps of Vale’s camp, then a blank wall of dark stone, then for a blink the bright canvas and gear again. A galvanized bucket appeared hanging in empty air and vanished before the drop of meltwater falling from it could land.

The transmitter kicked under Mara’s palm. A relay somewhere inside hammered itself into a frantic chatter.

Signe bent low, listening not with the headset now but with her teeth set together, feeling vibration through bone. “It’s not carrying clean. It’s skipping.”

Mara looked into the regulator socket again. The green living bridges between contacts had changed. They no longer pulsed with the three-tick pattern that had led them down here. They climbed and fell in uneven bursts, brightening when the seam widened, paling when the chamber cooled. One filament had split at the tip and was groping through air for a connection that wasn’t there.

The clatter from the tunnel stopped all at once.

Every grazer lifted its head.

Out of the dark behind them came a smell like split fern and wet pennies, overlaid with rot from somewhere deep and old. Not predator musk. Something larger, or stranger, or simply patient enough to have let the predators spend themselves first.

Vale saw the herd change and swore under his breath. “What comes now?”

No one answered. The question was too broad.

The first voice was Mara’s own.

“Don’t step there,” it said, sharp and close.

She spun toward the sound and saw herself across the chamber near the tunnel mouth—only not herself now. The other Mara’s hood was off, hair dark with sweat, one sleeve torn open to the elbow. Her face had the flat, stunned set of someone deep into blood loss. She raised one hand toward Elin.

Then the whole figure blew apart into drifting frost.

Signe made a sound Mara had never heard from her before, not fear exactly but fury at being made to see. “No.”

Mara’s stomach clenched once and went still. She could still feel, with sick clarity, the phantom memory in that impossible sight: the burn in the arm, the weakness in the knees, the knowledge of where not to place a boot. It had not felt like watching. It had felt like recall.

Elin did not look at her. “Tell me exactly what you saw.”

“Me. Hurt.” Mara swallowed. The air changed again, hot on one inhale, so cold the next her front teeth ached. “Near the tunnel.”

“Future?” Signe asked.

“Possible future,” Elin said at once, too quickly, as if speed itself might make the distinction hold.

The seam flashed. This time it showed not Vale’s camp but the surface—their orange marker poles half buried in drift, the sled line snapping in wind, the sky above the Antarctic plain white and depthless. For a blink Mara saw two figures climbing from a crack in the ice. Elin first. Signe after, dragging a pack. No third person.

Then that vanished too.

Signe had seen it. Mara knew because Signe’s breathing changed; it went shallow and disciplined, the way it did when she wanted very badly not to panic in front of the others.

“Elin,” she said, and her voice came out scraped. “Did you see—”

“I saw enough.”

“That wasn’t enough.”

“No,” Elin said. “It wasn’t.”

The room gave another lurch, not in stone but in sequence. Vale crossed from one side of the seam to the other and back again without moving his feet. Mercer’s rifle leaned against the shelf in three places at once. The grazer nearest the tunnel mouth stamped twice, and the sound came five beats later from the ceiling.

Mara shut her eyes for one second, opened them, and forced herself to the only thing in the room that still obeyed rules.

The set. Not all of it. Enough.

Its old iron case was too hot to keep a hand on. The gain knob could still be turned, but Signe was right: one hard push would cook the softened contacts. The left regulator was gone. The right hung crooked, its brass collar drifting with the machine’s vibration and changing the note of the hum. The green growth that completed the dead circuitry was alive, responsive, and now overstimulated to the point of damage.

It was not failing at random.

It was trying to carry too much.

Mara looked at the seam, at the wild alternation of cold and steam, at Vale’s camp tearing in and out of existence, and then at the little notebook Signe had tucked under a strap on her chest when she first took it from the 1938 shelf.

“Give me Vale’s log.”

Signe handed it over without question.

The pages were puckered and stained, the pencil gone silver in places. Mara flipped through swollen leaves until she found the cramped lines they had half read in the last clear stretch of time. Vale’s hand degraded as the entries went on. Tight field script became jabbed margins, strike-throughs, phrases crammed between lines.

attended or it weakens

cannot leave the set to itself during narrowing

Ross thought to kill current entirely; mistake

voice carries only if line held and field reduced together

Mara read the last line twice.

Elin had come to her shoulder. “There.”

“I see it.”

“Read it aloud.”

Mara did.

Signe stared at the machine. “Line held and field reduced together.”

“Not shut,” Elin said.

The words fell into place with a kind of dread simplicity. If they killed the transmitter, the seam would not neatly close. The warmth drop would hit the chamber, the field would collapse where it stood, and everything tied into it—the growth, the pressure, whatever balance held this underworld half alive—would tear with it. Ross had already proved that much. But leaving it as it was would widen the rupture until the cavern came apart or time itself stopped respecting edges.

“We don’t close it,” Elin said. “We retune it down while the line is still attended. Narrow the field without letting the carrier break.”

Vale heard enough through the skips to understand. His expression changed. Not surprise. Recognition. Something he had already learned by paying for it once. “That was the only way Ross and I thought might work.”

“And?” Elin said.

“And we were interrupted.”

The dark beyond the herd shifted.

This time they all saw it.

Not a body at first. A rearrangement of blue light. The hanging bulbs nearest the tunnel guttered out one by one, not because something struck them, but because something passed beneath and their glow withdrew from it. The grazers’ clattering started again, faster, overlapping in a brittle wave.

Mara could not make size from the dark. Only shape by subtraction. A broad, low front; multiple points of contact; a movement too smooth for stone. The herd did not split as they had for the predators. They closed ranks.

“Can they hold it?” Baines called from the far side.

No one answered him either.

Elin crouched by the transmitter and put two fingers lightly on the drifting regulator collar, just enough to feel its wobble. “If I seat this, the hum steadies. If it steadies, the seam may stop jumping.”

“Or the contact welds,” Signe said.

“If we do nothing, it cooks anyway.”

Mara looked again at the note in Vale’s hand. attended. line held. field reduced together.

Not one action. Several. And not possible from a safe distance.

The reset would need hands on the machine at the exact moment the seam narrowed. Someone to keep the regulator true as the load changed. Someone to feather the gain without surging it. Someone to keep the line attended even if the field bit back—because it would. Every earlier warning had pointed to that, all hidden under expedition understatement and field shorthand. Cannot leave the set to itself during narrowing. Ross thought to kill current entirely; mistake.

She saw it then as plainly as the brass threads in the knob shaft.

“You can’t do this and leave,” she said.

Elin’s hand stilled on the regulator.

Signe turned to her. “What?”

Mara hated how calm her own voice sounded. “During the reset. Whoever tends it has to stay at the shelf until the field finishes narrowing. If they let go too early, it tears loose again.”

“No,” Signe said at once.

Vale spoke over her, almost on the same breath. “Yes.”

The two words struck together like flint.

Signe wheeled on him. “You don’t get to agree.”

“I get to recognize my own mistake when I hear it.”

Mara kept her eyes on the machine. It was easier than looking at the crack the seam had shown them—the surface with only two figures climbing out. “It has to be manual. The machine isn’t stable enough to carry itself through. The regulator’s drifting, the contacts are soft, and the filaments are compensating live. If no one’s here to trim it as the load changes, it will either go dead or flare wide.”

“Elin can talk you through from the far side,” Signe said. “We rig something. A brace. Wire. A clamp.”

“With what?” Elin asked quietly.

Signe opened her mouth. Shut it. Looked around at the wrecked shelf, the cracked stone, the old transmitter built in a decade when equipment assumed men had time and patience and spare parts. There was wire, yes. Rusted clips. A hand crank. Melted insulation. Nothing precise enough to replace a living hand making corrections by feel.

The chamber air went abruptly lush and wet. Mara smelled leaf mold, pond water, crushed green stems. Vines she had never seen brushed her wrist.

She jerked back.

For an instant the cavern had become something else entirely—a hothouse ruin thick with broad, waxy leaves climbing the iron posts, the black stone split by roots. In that boiling green vision the transmitter shelf still stood. A figure sat beside it in shirtsleeves, one hand on the gain, face turned away. Bones showed white through the torn cloth at the wrist where the skin had gone.

Mara blinked and the plants were gone. Stone again. Steam and rime.

Signe had seen some version of it. “Mara.”

“I know.”

Elin drew one careful breath. Then another. She did that when building a procedure under pressure, stacking steps where fear wanted to flood. “Listen to me both of you. We are not deciding who stays. We are deciding what has to happen first.”

Mara almost laughed at the difference. It was a very Elin sentence: move the door three inches to the left so no one could yet see they were standing in it.

Elin pointed, not looking at either sister. “One: stabilize the right regulator enough to stop the jumping. Two: re-establish a clean line to Vale’s side. They have to send the warning that started all this, or the loop never locks. Three: narrow the field in controlled increments while the transmitter remains attended. Four: everyone not on the shelf clears the chamber before the temperature swing breaks the floor.”

Vale’s face had gone very still. “The warning.”

“The signal,” Mara said. “The call sign. The plea for help. It has to be sent from your side at the right settings, through the narrowed field. That’s what reached us.”

“And brought you here,” Baines said.

No one touched that.

Mercer leaned into view past the seam, soot on his forehead, blanket still in his hands. “If the warning is what forms the line, and the line is what lets you narrow it—”

“Then it was always this,” Elin said.

The larger thing in the tunnel came on.

Not fast. That was worse. The grazers’ front rank braced, feet planted wide, tooth-clatter rattling through the floor. A blue bulb popped above them with a wet snap, spraying hot phosphor against the stone. In that blink of light Mara caught part of the approaching shape: a plated shoulder or carapace, translucent at the edge like old fingernail, with fronds or tendrils trailing beneath that combed the ground as it moved.

Signe lifted the empty flare pistol anyway.

Mara took the old expedition log from under her arm and set it on the shelf beside the transmitter, weighing one swollen page open with a cracked porcelain insulator. She turned the book so Elin could see the line again.

cannot leave the set to itself during narrowing

She did not have to point.

Elin read it. Read it again. Her jaw worked once.

The seam flickered and showed the surface a second time. Two figures in white crossing a plain under weak sun. The image was farther off now, blurred by drift. One of them stumbled. The other did not turn back immediately.

When it went away, the chamber seemed smaller.

Signe saw where Mara was looking and stepped between her and the posts, as if she could block the idea itself. “No.”

Mara met her eyes then. At last. “I didn’t say anything.”

“You don’t have to.”

The thing in the tunnel pressed against the herd line. The first grazer gave ground with a cry unlike any sound it had made before—high, almost birdlike, full of pain and outrage. The rest answered by slamming their forefeet down in unison. The impact traveled through the cracked floor and into the shelf. The right regulator shivered loose another fraction.

Elin caught it with her fingertips.

“Enough,” she said, and there was iron in it now. “We do the next task. Mara, work out the tuning range we can survive. Signe, strip anything usable from the spare wiring and the crank box. Vale—get your men ready to send on my mark. If this comes apart before we begin, none of the choice matters.”

Mara nodded because nodding was easier than speaking.

But the knowledge had already entered the room, and rooms never forgot once they had made space for a thing.

One person at the shelf.
Hands on the machine.
Field narrowing.
Everyone else gone or trying to be.

At the tunnel mouth, under failing blue light, the grazers folded around the dark advancing shape like pale reeds before a submerged wheel, and the chamber floor began to pulse beneath their boots with a slow, gathering beat that did not belong to any heart Mara wanted to imagine.

The right regulator was hot enough to sting through Mara’s glove.

She held it in place with the heel of her hand while Signe fed stripped copper from the crank box around the cracked housing. The wire had gone black-green where the growth touched it. It twitched like root hair when Signe cinched it down.

“Again,” Elin said.

Vale’s voice came through the transmitter in a wash of static and relay chatter. “Receiving.”

“Not clean,” Mara said.

The seam between the iron uprights shivered, showing half a tent wall, then black stone, then the edge of Baines’s shoulder in wool and canvas. The chamber flexed cold, then wet. Frost silvered the transmitter key. A second later beads of warm water ran down the same metal and hissed where they met the filaments.

Out in the tunnel the herd struck the floor in a slow common rhythm. Not panic. Work.

Mara adjusted the gain by the width of a thumbnail. The relay’s frantic clicking dropped into a rougher cadence. “Now.”

Elin leaned toward the posts, one hand braced on the stone shelf. “Vale. On my mark, your call sign first. Then the plea. Exactly as sent before. No improvising.”

Mercer appeared behind him, pale under soot. “You want him to sing from a grave and keep time as well.”

“Can he do it?” Elin asked.

Vale did not look away from Mara. “Yes.”

The thing in the tunnel moved nearer. The grazers’ tapping broke apart, scattered, then re-formed farther in, making a crooked lane toward the chamber. A smell came with it now, rank and mineral, like split shell and hot pennies.

Signe finished the wire lash and sat back on her heels. Sweat had pasted loose hair to her temple. “It’ll hold if nobody breathes on it.”

“That’s almost comforting,” Mara said.

Elin took the receiver earpiece from around her own neck and pressed it at Mara. “Find the range.”

Mara listened. Static hiss. Tick. Tick. Tick. Then, under it, a second texture, a thinning and thickening like someone drawing a blade down ribbed glass. The seam pulsed each time it sharpened. Too low and the line smeared into noise. Too high and the filaments woke bright enough to spit green sparks from the transmitter screws.

She eased the knob upward until the hum in the shelf matched the stomping from the tunnel, then a hair back.

“There,” she said.

The machine answered under her palm with a steadier vibration, unpleasantly alive. Not a radio anymore. A held-open wound with brass fittings.

Elin heard the change too. She did not nod, only said, “Good. We move to the ledge.”

Mara kept her hand on the set. “You move.”

Signe looked up fast. “No.”

“Elin needs both hands clear for the calibration.” Mara did not look at them. If she did, it would turn into a family argument, old and stupid and useless. “The shelf is the worst place in the chamber once you start narrowing. We know that. We also know the machine has to stay attended. I’m already here.”

“Mara,” Elin said, and that tone was worse than shouting.

“It’s arithmetic.”

“It is not.”

The tunnel gave them no time for refinement. One of the grazers screamed—a thin tearing note—and a heavy impact shook powder from the ice ribs overhead. At the edge of the blue dark something broad shouldered against the herd line. Plates caught the bioluminescence and shed it in milky bands. Tendrils or feelers swept low across the floor, reading it.

Baines swore on the far side. Mercer lifted the old rifle.

Vale stepped through the seam before anyone told him not to.

He came raggedly, the field taking him in jerks. For one blink he was doubled, one body in each decade with the iron post cutting through his ribs like a spear, and then he was entirely in Mara’s chamber, stumbling to one knee on wet stone. His cheek was caked with old blood. One sleeve hung shredded.

Elin made a sound from the back of her throat and went for him, not to help but to drive him back. Vale caught her wrist.

“No,” he said.

The word landed hard because he spent nothing else around it.

He got up, favoring one leg, and put a hand on the transmitter beside Mara’s. His skin was grey with fatigue, beard dark at the jaw, eyes much older now than when she had first seen him through the seam. “This began in my care.”

“Don’t romanticize yourself,” Mara said. “We need hands, not speeches.”

His mouth twitched once. Not amusement. Recognition.

He looked at the machine, at the growth braided through the contacts, at the iron uprights breathing light. “You know how to set it,” he said. “I know how to keep sending when it starts to pull.” He turned his head enough to include Elin and Signe. “And if I am wrong, I am less expensive to the future than she is.”

Signe took one step toward him, hands balled. “Don’t say things like you’re a package to be inventoried.”

“Then don’t waste time objecting.”

The larger creature hit the herd properly then.

The chamber answered in pieces: clatter of many feet, a wet crack, a gust of hot carrion stink. Two grazers burst from the tunnel mouth and skidded across the chamber floor, one with a section of flank peeled open white and glistening. Behind them came the predator, too large now for the neat word. It moved on six low jointed limbs under a plated body the color of old candle wax, its forward plates translucent at the edges, mouth hidden beneath a curtain of moving feelers until it raised itself and the nested jaws opened and flashed wetly in the blue light.

Mercer fired through the seam. The report came flattened, delayed, as if the years had to carry it by hand. The bullet struck stone behind the creature. It turned not to the sound itself but to the impact burst, then lunged.

Elin shoved Signe backward toward the side ledge. “Go.”

“No.”

“That wasn’t a request.”

Mara stripped off one glove and put her bare fingers on the gain. Skin gave better truth than leather. The knob burned. “Vale,” she said. “If you take it, don’t chase the signal. Let it come through the noise. Narrow on the third tick, not the voice.”

He looked at her hand on the brass, at the blanching skin. “I understand.”

She believed him. That was the dangerous part.

The wounded grazer found its feet and hammered both forelimbs down. The others in the tunnel answered, and for an instant the whole floor carried one enormous false heartbeat. The predator veered toward the vibration, slipped in meltwater near the steam crack, recovered with horrifying grace, and came on again.

Baines shouted from the other side. The seam widened and pinched around his crate as he shoved it through. It emerged half-charred by field heat and struck the predator’s shoulder. Plates rang. Not enough.

Vale closed his hand over Mara’s at the gain knob.

For a second neither moved.

Then Mara let go.

The pain came at once, blood returning to her fingers in a savage rush. She stepped back and hated the relief in it. Vale took her place square to the machine, one hand on the gain, the other on the key. He set his jaw like a man about to endure dentistry with no ether.

“Elin,” he said without looking up, “do the rest.”

She was still staring at Mara as if willing her by anger alone to reclaim the shelf.

Mara nodded once. It felt like cutting rope.

That, more than anything, made Elin move. She grabbed Mara by the forearm and shoved her toward the ledge path worn into the wall beyond the uprights, a narrow rise of black rock above the shelf where the temperature swings would hit less directly if the field folded wrong. Signe was already there, receiver around her neck, crank-box wiring looped over one shoulder like entrails.

“Both of you,” Elin said. “Up. Keep the line clear.”

“And you?” Signe said.

Elin looked at the seam, at Vale, at the advancing thing. “I calibrate from here until I can’t.”

The predator came across the chamber in a sideways rush, feelers combing. Mara snatched the flare rifle from the stone where she had dropped it and fired from the ledge without shouldering properly. The flare struck one front plate and burst, smearing the creature in hard white fire. In that magnesium instant the chamber split around them.

Surface.

Camp tent.

Stone shelf.

A man in 1938 wool with his face blown white by light.

A modern aluminum sled half buried in drift.

The iron posts standing in all of them.

Mara saw the receiver on the workbench at their camp module. Saw herself hunched over it in a different coat, head bent, listening. The image snapped away before she could draw breath.

The predator recoiled from the flare and slammed instead into the transmitter shelf. The whole machine jumped. The right regulator screamed—a kettle shriek made of metal rather than steam—and green sparks lashed out in a fan.

Vale did not lift his hand.

“Elin,” Mara shouted.

“I know.”

Elin crouched beside the iron upright and turned the calibration collar with the butt of her ice hammer, one notch, then back half, eyes on the seam. She was counting under her breath. Signe had the receiver pressed hard to one ear, repeating the intervals: “Three apart. Pause. Three apart. Still clean. Still clean.”

On the far side Mercer cranked. Baines held the line wire clear of the floor. Canvas in Vale’s camp bellied inward as something struck it and raked down.

Vale began to transmit.

First the call sign, clipped and formal despite the blood at his mouth. Then again. Then the three ticks that had haunted the dark under all their days. He listened between bursts, made a minute correction at the gain, sent it again.

The chamber changed on the sound.

The blue growth along the wall fronds woke in bands running away from the shelf. Not random now. Intent. The seam smoothed from a ragged rent into a plane that almost looked man-made, a vertical skin of moving air held taut between the posts.

Mara felt the loop close before she understood it. The room had been waiting for its own answer.

Signe heard it too. Her face went white under the sweat. “That’s it,” she said. “That’s what we recorded.”

No one told her to keep going. She already was.

Vale keyed once more, and this time the plea came after the call sign with no hesitation, no dignity left in it. Help me. Then again, flattened by the set into Help. A little more static took the edges each time. By the fourth sending it was almost exactly what had come through the headphones at camp.

Mercer looked across years and understood as his own voice was being made into history. He stopped cranking for one stunned beat.

“Don’t stop!” Elin shouted, and her voice crossed into his room a fraction late.

He bent to it again.

The predator had recovered from the flare. It did not charge now. It circled, reading the chamber through its feelers, choosing among the impacts and hums. Smarter than the others, or older. The herd bunched at the tunnel mouth, not entering, not fleeing. Watching.

The floor temperature dropped so fast Mara’s wet cuff stiffened. Frost raced over the lip of the stone trough. Then heat surged back, enough to steam from Vale’s shoulders.

“Elin,” Signe said sharply. “It’s narrowing too fast.”

“I know.”

“You’ll shear the seam.”

“I know.”

Vale kept transmitting through it all, voice growing hoarse, key tapping under his fingers, then the spoken plea again on Elin’s mark. Call sign. Ticks. Help. Call sign. Ticks. Help. The pattern drove into the chamber like nails.

The predator chose the shelf.

It came low and sudden. Mara fired her last flare and missed wide; the shot burst against the far wall and drenched the fronds there in sour white fire. Elin swung the ice hammer at the creature’s feelers, not to injure but to make a sharp impact off the post. It snapped toward that instead and crashed shoulder-first into the iron upright.

The seam boomed like a struck drum.

On the far side Baines vanished from view. Mercer went down. The line wire whipped. Vale lurched but held the gain.

“Now!” Elin shouted.

Signe yanked the calibration lead free.

For one impossible second everything aligned.

The seam narrowed to a slit no wider than a door standing ajar. Through it Mara saw not Vale’s camp, not the flicker of alternate stone, but daylight. Open white above a split in the ice. Windblown snow crossing it in streamers. The surface.

Elin saw it too. “Go!”

Signe did not argue this time. She grabbed the logbook where Mara had left it on the shelf edge and ran the ledge down toward the seam. Mara followed, then turned because of course she did, because leaving always had to be torn from her.

Vale was still at the transmitter.

The predator had hooked one plated limb over the shelf and was hauling itself up, mouth opening under its curtain of feelers. Green filaments burned around Vale’s wrist where the machine had begun to cook through skin and cloth alike. He did not seem to feel it. Or felt it and had no budget left for reaction.

“Vale!” Mara shouted.

He looked up at her through the heat shimmer.

Not brave. Not resigned. Simply there.

“Go,” he said, and sent the call sign once more.

Mercer had reached the seam from his side and was dragging Baines by the collar toward the narrowing bright. Behind them the 1938 camp was failing, lines of it pulling loose like wet paper. Canvas, lamp, coil of cable, all flattening into light.

Elin seized Mara’s jacket and shoved her bodily toward the opening. “Do not make this about you.”

It was the cruelest thing she could have said, and because it was her sister, it worked.

Signe went through first, vanishing into white glare. Elin pushed Mara after, one hand between her shoulder blades. The seam skin touched Mara’s face like hot silk and then like river ice and then she was half through, one boot striking packed snow instead of stone.

Behind her the chamber gave a sound like a mountain cracking in its sleep.

Mara twisted back.

Vale had finally taken his hand from the key. The transmitter was no longer humming; it was roaring. The predator surged over the shelf. Vale seized the iron frame of the set with both hands and drove himself and the machine sideways together into the uprights.

Not away from the attack.

Into the seam.

Light folded inward.

For an instant Mara saw too much at once: the camp module receiver glowing under her own hand days ago; Ross or some other dead man under falling ice; a line of pale grazers crossing black stone under fern-blue lamps; Vale at the key in 1938; Vale at the key now; the crack in the surface waiting above them before they had ever stepped on it.

Then Elin hauled, and the world narrowed to cold wind and crusted snow and the taste of copper in Mara’s mouth.

She fell hard onto the surface beside Signe. The fissure gaped in the ice like a wound stitched open. Warm vapor poured from it in one last breath. Elin came through on hands and knees, rolled, and reached back automatically.

No one took her hand.

The opening had already shrunk. Not collapsed, not yet. It had become a thin vertical seam of light sunk into the ice, no broader than a knife blade, humming faintly under the wind.

Mara crawled toward it.

Elin caught the back of her harness and held on with both hands.

“Mara.”

Inside the seam there was no chamber now. No transmitter shelf. Only moving brightness and, once, the suggestion of a figure very far down in it, walking where no floor should have been.

Then the light thinned. The hum failed. Snow whisked across blue-white ice.

Where the fissure had been, there remained a line no deeper than a score mark from a skate blade, already filling with drift.

No one spoke for several breaths. The sky above them looked cheap and unreal after the underworld light, a flat white lid.

Signe was the first to move. She had the logbook jammed under her coat, both arms wrapped hard across it as if it might get up and leave. Blood from a split lip had dried black on her chin. She stared at the sealed line in the ice and said, very softly, “He sent it.”

Mara could still hear it. Not in memory. In her bones. The three ticks. The clipped call sign. Help.

Elin let go of Mara’s harness only when she was sure Mara would not throw herself back at the ice. Her hand stayed resting there a moment longer than necessary, fingers cramped and shaking.

Below them, or beyond them, somewhere under the miles of old cold and black stone, something answered with a single distant knock.

Then nothing at all.

• Elin slapped Mara hard enough to turn her head.

• Not from anger. From triage.

• “Stay here.”

• Mara blinked at her, one pupil wider than the other, copper blood at the corner of her mouth. The flat white above them had begun to spin into weather again. Wind lifted streamers of drift over the sealed cut in the ice and erased their tracks as fast as they made them. Signe was already on one knee at the half-buried sled case they had hauled down with them, fighting a zipper gone stiff with frost and melt, gloved fingers slipping on the teeth.

• “We need the beacon,” Elin said. “And the spare battery if it didn’t crack.”

• Mara pushed up as if she had not heard her. “The line was here.”

• Elin caught her by the front of the harness and shoved her back down. “The line is gone.”

• For a second Mara’s face went flat and far away. Then she let Elin’s hand stay where it was.

• Signe tore the case open. Inside, foam cradles had shifted. The handheld radio was wet under a skin of rime. One flare tin had burst loose. The emergency locator still blinked, dim and stubborn.

• “Working,” Signe said. “Maybe.”

• “Maybe is enough.”

• Elin snapped the beacon on and jammed it upright in the snow. The little mast leaned in the wind and winked toward satellites none of them could see. She stripped one glove with her teeth, pressed two fingers against Mara’s throat, counted. Fast. Too fast, but regular.

• “Mara.”

• “I know what his hand looked like.” Mara’s voice had gone distant and precise, as if she were reporting on a body. “The burns were across the knuckles first, not the palm.”

• Elin stared at her.

• Signe stopped moving for just one beat, receiver in hand.

• Then Elin said, “Don’t do that now.”

• Mara looked from one sister to the other. “What?”

• Neither answered.

• The wind thickened. Not a true whiteout yet, but building toward it with intent. Their camp lay less than a kilometer away by the bamboo flags they had put in on the approach, assuming the flags still stood and the world had not chosen to simplify itself.

• Signe dug out the old headset receiver, the modern one with the cracked Bakelite earcup and the loop lead wrapped round the body. It had taken blows, water, heat. A section of insulation had bubbled and split. She held it as if it might either prove everything or humiliate her.

• Elin got Mara to her feet. “Can you walk?”

• “Yes.”

• “That isn’t what I asked.”

• Mara flexed both hands. The right one obeyed. The left was slower. “I can walk.”

• Good enough. Elin hooked the sled line over her shoulder, checked Signe’s coat zip, then pointed with her chin. “Markers.”

• They moved.

• There was no heroism left in any of it. Only the ordinary ugliness of survival: lungs pulling knives of cold after greenhouse heat, wet base layers turning clammy under outer shells, one boot biting at the heel with every step because the lace had frozen in a twist. The sealed seam remained behind them somewhere under new drift, not even a scar at this distance. If there had been any sign at all, the wind wanted it.

• Signe kept glancing at Mara.

• Finally Mara said, without looking back, “Ask it.”

• Signe swallowed. “When he drove the set into the uprights.”

• “Elin said your name,” Mara said. “Not mine.”

• Elin stopped so abruptly the sled nosed into the backs of her legs.

• “No,” Elin said.

• Mara turned. Her lashes had iced white at the edges. “You told Signe to go. Then you put your hand on my shoulder.”

• Signe’s face emptied.

• “Elin,” Mara said softly, and now there was something in it worse than accusation, because it was careful. “You said, ‘Don’t make this about you.’”

• “I said that to you.”

• “You said it to Signe.”

• The wind hissed over the crust between them.

• Signe looked at Elin first, then away. That movement told its own story. Elin felt it like a puncture.

• “We are not doing this out here,” Elin said.

• “Because I’m wrong?”

• “Because we need shelter.”

• Mara opened her mouth, then closed it again. Not yielding. Storing it.

• They walked on.

• By the time the first orange marker showed through the blowing white, camp looked indecently normal. Two low modules hunkered on their skids, drifted nearly to the lower windows. The generator mast stood where it should. A prayer flag of torn survey tape snapped from the fuel cache. The sight of it made Elin so angry she nearly laughed.

• Inside the main module the air was stale, metallic, faintly sweet from leaked antifreeze. Signe got the diesel heater coughing alive while Elin stripped Mara out of her shell and checked her for fresh blood. There was none. A bruise was rising black-green along the ribs where the predator had thrown her days—or an hour—before. Time had gone granular. Elin no longer trusted the size of it.

• “Tea,” Signe said hoarsely to nobody, and set a pan of meltwater on the ring.

• Mara stood in her thermal layers in the middle of the narrow space, dripping onto the vinyl floor. Her eyes kept snagging on things: the hanging mug net, the field maps taped by the table, the rag they used to wipe down goggles. She frowned at the maps.

• “That wasn’t there.”

• Signe turned. “What?”

• Mara pointed at the red grease-pencil circle around the sub-ice anomaly.

• Elin answered before Signe could. “I marked it yesterday.”

• “No,” Mara said. “You used blue.”

• The kettle began to shiver on the burner.

• Signe pulled the logbook from under her coat. The waxed canvas wrapper had gone almost black with wet. She laid it on the table as if laying down a charge sheet. There it was: T.V.E. stamped faintly into the leather, edges bloomed and swollen, pages warped with age and melt. Real enough to weigh something. Real enough to burn, if anyone unwisely set a match to it.

• “We have this,” Signe said.

• Elin let out a breath through her nose. “We have a rotten notebook from a dead expedition and three people with exposure and a story that gets worse every time you tell it.”

• Mara smiled once, without humor. “Then tell it less badly.”

• The kettle gave a hard click and spat. Signe poured into metal cups, sloshing most of one because her hands had finally started to shake.

• Elin took the receiver from her. “Sit.”

• Signe obeyed because she was too tired to make a principle out of anything.

• Elin unscrewed the receiver’s back plate with the blade of a camp knife. One terminal had pulled half free. Greenish residue furred the contact point where the cavern growth had bridged metal it had no business touching. She scraped it gently. The smell that came off was wrong for electronics alone: hot copper and pond water.

• Mara leaned over her shoulder. “Don’t clean all of it.”

• Elin looked up sharply.

• “It changed the circuit,” Mara said. “Or completed it. Not permanently. But enough.”

• “That your expert opinion now?”

• Mara’s gaze stayed on the receiver guts. “He had to wet the cloth under the right regulator before touching the key again.”

• Signe said, “Vale didn’t do that.”

• Mara looked at her. “Yes, he did.”

• “No.” Signe pushed the cup aside. “Mercer did. Vale’s right hand was already burned.”

• Mara’s face lost color under the windburn. For the first time she looked frightened, not by what was under the ice but by what was happening in the room.

• Elin set the receiver down carefully.

• The heater ticked. Meltwater ran off their abandoned outer layers into a tray by the door.

• Signe opened the logbook to the pages she had read before. Others had loosened in the damp, their ink feathered into threads. Her fingertip moved over Vale’s hand, the tight educated script marching down the page with all the authority of someone sure writing can nail a thing in place.

• January 27. Attended, always attended.

• January 29. Ross insists—

• The next line was gone into a brown tide mark.

• Signe turned another page. A pressed bit of blue-white frond dropped out, brittle as ash. All three of them watched it on the tabletop.

• Elin said, “Bag that.”

• Signe reached for a specimen envelope, then hesitated. The frond, once detached, had begun to dim. Not because light was leaving it—because there had never really been much of its own. It was like watching a thought fade from a face.

• Mara whispered, “Don’t.”

• Too late. Signe touched it with forceps.

• It crumbled into wet grit.

• Nobody moved.

• Then the radio on the shelf cracked once with a burst of static so sudden they all flinched.

• Not the old receiver. The camp set.

• Elin crossed the room in two steps and snatched up the handset. “Gamma camp. Say again.”

• Only carrier hiss answered, then a clipped, distant voice from base, chopped by weather and range: “—repeat your beacon activation. Repeat, Gamma, confirm status.”

• Elin shut her eyes once. Relief made her vicious.

• “Gamma confirms three alive,” she said. “Repeat, three alive. We need med evac and retrieval at the extension marker route. Surface instability at our last coordinate. I say again, unstable.”

• A blur of questions came back through static. Injuries. Fuel. Shelter integrity. She gave them what mattered and lied about what didn’t.

• “No, no missing personnel. No fire. No, we are not remaining at source point.” Her mouth tightened around that one. “You will not bring a heavy crawler over the final half kilometer until we mark safe approach.”

• Signe mouthed, Good.

• Base kept talking. Elin listened, answered, set expected weather windows, battery status, frequency checks. By the time she hung the handset back on its cradle, the room had narrowed into procedure again. It helped. It always had.

• Mara was at the table with the old receiver in her lap.

• “Elin,” Signe said quietly.

• Mara had found a roll of solder wire, though the iron was cold. She was winding the wire around the damaged terminal by hand, following some remembered geometry. Not random. Not repair, exactly. A shape.

• “What are you doing?” Elin asked.

• Mara did not look up. “It likes a loop.”

• Signe’s throat worked. “Mara.”

• Now Mara looked up. There was apology in her face, and embarrassment, and something harder to name. “I know how that sounds.”

• “You don’t get to touch bare contacts again,” Elin said.

• “I’m not planning to.”

• “Not planning,” Elin repeated. “Excellent.”

• Mara sat back. The shape she had made was crude, but it echoed the little portable loop antenna they had used on the ice. Elin hated that she saw the resemblance immediately.

• Wind hit the module broadside. The wall gave a small aluminum boom.

• Signe said, “If our memories don’t match, that doesn’t mean the event changed. It can mean stress. Hypoxia. Temperature swing. Shock.”

• “Yes,” Elin said.

• Mara nodded too quickly. “Sure.”

• Signe tapped the open logbook with one fingernail. “But if the field narrowed by using an existing line—”

• “Elin,” Mara said.

• Elin had already heard it.

• Not through the speaker. Through the table.

• A tiny tapping. Three beats, evenly spaced.

• All three of them went still.

• Again.

• Tick. Tick. Tick.

• It was coming from the receiver in Mara’s lap.

• Nobody breathed.

• Then a fourth sound entered under it, faint as an insect wing: carrier hum.

• Mara set the receiver down with exquisite care on the table between the cups. The broken terminal she had looped by hand had begun to glow with a dull green bead no bigger than a pinhead. Not hot enough to smoke. Not yet.

• Signe’s face had gone white. “That’s impossible.”

• Elin reached for the battery lead and stopped an inch short. Rules. Costs. Attended.

• The hum thinned, returned. Three ticks.

• Then, through a wash of static and distance and something like water moving under stone, a voice almost formed. Male. Tired. Not Vale this time, or not only Vale; the years had rubbed over it.

• Can—

• The rest broke apart.

• Mara’s hand hovered over the set, trembling.

• Elin said, very level, “Do not touch the gain.”

• “There is no gain.”

• “Then do not invent one.”

• The green pinprick at the terminal brightened and went out. The room seemed to exhale with it.

• Silence.

• Signe made a sound in the back of her throat that might have been a laugh if it had not been so close to crying. “No one is going to believe us.”

• Elin was still watching the dead receiver. “That was never the useful question.”

• Mara looked toward the buried world under their boots, as if there were a direction to look in. Her face had changed in the last few minutes. Not healed. Not steadied. Aligned, perhaps, with some argument only she could hear.

• “We don’t mark the route for them,” she said.

• Elin turned. “Base is sending a team.”

• “We mark the safe approach to camp. Not the source.”

• Signe stared at Mara, then at the logbook, then at the receiver. “You think it’s still there.”

• “I think gone and hidden are not the same word.”

• Outside, the wind worried at the module seams. Inside, meltwater ticked from a sleeve cuff into the tray. The old receiver sat between them like a small, ugly animal pretending to be dead.

• Base called again on the shelf set, sharp with static, asking for the exact coordinates of the collapse site.

• No one answered at once.

• Then, from the receiver on the table, so faint they nearly mistook it for settling metal, came the three measured ticks again from somewhere under a mile of ice.