The Chamber at Three Hundred

• Chapter 1 Beneath the Threshold
• Chapter 2 Three Hundred Meters
• Chapter 3 The Fracture
• Chapter 4 Living in Saturation
• Chapter 5 Heliox Whispers
• Chapter 6 System Failure
• Chapter 7 Sealed In
• Chapter 8 The Wiretapped Bell
• Chapter 9 Pressure Drop
• Chapter 10 Suspicion at Depth
• Chapter 11 Poisoned Mix
• Chapter 12 Tipping Point
• Chapter 13 The Saboteur's Hand
• Chapter 14 Lockout
• Chapter 15 Cold Contamination
• Chapter 16 Dark Currents
• Chapter 17 Oxygen Toxicity
• Chapter 18 The Living Trunk
• Chapter 19 Trapped Alive
• Chapter 20 The Last Regulator
• Chapter 21 False Atmosphere
• Chapter 22 Blowout Protocol
• Chapter 23 High-Pressure Standoff
• Chapter 24 Emergency Venting
• Chapter 25 The Final Chamber
• Chapter 26 Surface Tension

The hatch did not bang shut so much as it ceased to exist as a door. It was twelve inches of forged steel faced with a gasket of nitrile rubber that smelled faintly of rotten lemons and hydraulic fluid. When Keith Vance dogged it down, turning the brass-spoked wheel until the threads bit into the frame with a dry, mechanical screech, the outside world vanished into an abstraction of numbers on a console sixty feet above their heads.

There were four of them inside the living tube of the saturation complex, sitting on bunks narrow enough to punish an unsettled sleeper. The chamber measured eight feet in diameter and twenty-two feet from the inner hatch to the sanitary lock at the far end. It was painted an off-white that had long since yellowed from the steady seep of skin oils, steam from the hot-water mugs, and the fine film of lubricating grease that migrated everywhere, airborne or tracked on the soles of neoprene slippers.

"Blow down starts in three," Vance said, checking his watch against the bulkhead clock. The clock was an analog brass Hamilton, bolted through the hull with vibration dampeners so the ship’s engines didn’t shake its balance wheel to pieces. "Life Support says the pump room is lined up. Jonas, check the floor drains. If the balls haven't seated, we’ll smell the bilge the whole way to the seabed."

Jonas Lind, the youngest of the four by five years and the only one whose knees didn't click when he crouched, kicked the brass cover over the center scupper. It gave a dull, leaden ring. "Seated," he said. He sat back down on the bottom tier, his long legs folded nearly to his chin. "How's the top end looking, Keith? The swell felt heavy when we stepped off the deck."

"Seven meters," Vance said. "The rig’s thrusters are running forty percent to hold station over the manifold. You won't feel it in five minutes anyway. Down here, sea state is just something that happens to other people."

He didn't mention the groan that had shuddered through the deck plates of the Aegir Discoverer just as they’d climbed the ladder through the moonpool mezzanine. A supply boat had clipped the stern bumper three days ago during the gale, and the diving superintendent had been swearing into his headset about a bent thruster fairing ever since. But once the steel was sealed, you didn't talk about ships. You talked about bar, percentage points of oxygen, and whose turn it was to wash the tin mugs in the half-sink by the transfer sleeve.

Across from Vance, Miller was already taping a photograph of a red setter to the curved steel above his bunk, using round dots of mastic that wouldn't off-gas into the scrubbers. Miller was thick-shouldered, with ears that looked like they had been chewed by an impatient terrier, and twenty years of North Sea nitrogen in his joints. He didn't look at Lind or Vance. He just patted the dog's picture twice with the heel of his hand and lay back, his hands laced behind his head.

"We have twelve hours of descent," Miller said to the ceiling. "Nobody eat the beans from the dinner tray. The scrubbers can handle carbon dioxide, but they don't do miracles for Lind's guts."

"The beans were cold anyway," Lind muttered.

The fourth man, a contract specialist named Aris Thorne who had arrived by the morning chopper from Aberdeen with a Pelican case handcuffed to his duffel, sat on the small metal bench near the inner door. He was thin, forty-odd, with graying stubble that stopped abruptly along a neat jawline and eyes that moved over the pipe runs like an auditor looking for a missing column of figures. He had not spoken since they cleared the airlock, except to give his weight and blood pressure to the chamber tender through the brass communication horn.

"Mr. Thorne," Vance said, leaning his elbows on his knees. "First time in a six-man spread?"

"Third," Thorne said. His voice was flat, dry as shavings. "Last was the Brent Field, five years back. We didn't have the new soda-lime canisters on that stack."

"Well, you’ll like these," Vance said. "They only taste like chalk for the first four hours. After that, your tongue goes numb and everything tastes like warm lard anyway."

The intercom clicked, a sound like a small dry branch snapping underfoot. A voice came through the overhead horn—squawky, thin, stripped of bass frequencies by the tiny diaphragm.

"Chamber One, this is Control. We have seal confirmation on outer dogs. We are commencing pressurization on mixed gas at eighteen meters per hour equivalent. Divers, begin your clearing cycles. Good journey down, boys."

"Understood, Control," Vance said toward the grille. "Give us the juice."

The sound began not as a roar, but as a hiss—the high, needle-thin whistle of seventy bars of helium rushing through three-quarter-inch stainless steel tubing behind the panels. The temperature in the chamber jumped immediately.

Gas compression is simple physics: cram more molecules into a fixed volume and the kinetic energy has nowhere to go but out as heat. Within ninety seconds, the cool sea-air draft that had lingered from the deck was replaced by a close, suffocating tropical swamp. The skin on Vance’s forearms prickled with sudden sweat. He peeled off his wool sweater, revealing graying underarms and the faded blue ink of a tattoo he’d gotten in Peterhead when he was nineteen—a pair of crossed diver’s knives that now looked more like two butter knives forgotten in the sun.

"Pinch and blow," Vance reminded them, though none of them needed it.

He held his nose, mouth shut, and puffed his cheeks. Click-pop. The eardrums adjusted with the dry, tearing sound of wet parchment being separated. Lind was already doing it rhythmically, his eyes closed, his head rocking side to side like a man listening to a slow waltz only he could hear. Miller didn't even move his hands; he had the knack of clicking his Eustachian tubes by shifting his jaw, a trick Vance had never managed without biting his own tongue.

Thorne reached up and felt the skin behind his left ear. He winced once, then his jaw moved with an audible snap.

"You have a bad sinus, speak now," Vance told him. "We hit thirty meters, it’s not an inconvenience anymore, it’s a hemorrhage."

"I’m clear," Thorne said. His fingers dropped back to his lap.

The pressure mounted with an almost physical weight, not pressing against the chest from the outside—because the lungs took in the same density of gas—but settling into the marrow. The air grew visibly thick, hazy with moisture that couldn't condense against the sweating steel walls. As the helium concentration rose, replacing the heavy, soporific nitrogen that kept men stupid on the deck, the voices began to drift.

It was subtle at first. A tightening of the timbre, as though everyone had developed an abrupt, minor head cold.

"They're using the bottom manifold from the Vanguard," Miller said, his eyes still closed. "The bypass valve is four-inch, not six. We'll need the long-reach sockets if we’re going to flange that blind."

His voice sounded like a schoolboy trying to imitate his father through an empty toilet paper roll. Lind snorted, the sound emerging as a ridiculous, reedy whistle.

"Don't start," Miller warned, though his own lips twitched. "I don't need a twenty-year-old giggling at my register. We’ll all sound like geese before midnight."

"It's the Donald Duck act that kills the dignity," Lind squeaked. His voice had jumped an entire octave, thin and absurdly cheerful, contrasting with the dark circles under his eyes. "You spend four weeks in here, talk to your wife through the unscrambler, and she thinks you’ve been replaced by a ventriloquist's dummy."

"Your wife knows you're a dummy anyway, Lind," Vance said. He stood up, stooping under the overhead pipe runs.

The chamber ceiling was an iron jungle. There were three separate lines for the breathing loop—supply, exhaust, and secondary cross-over—all lagged in white neoprene with red and green indicator tape every six inches. There were the hydraulic lines for the outer dogs, the small copper capillary tubes running to the pressure gauges, and the thick, rubber-sheathed umbilical that carried electrics for the scrubbers and the communication set. Every six feet, a round brass deckhead light burned through a thick lens of borosilicate glass, casting shadows that were hard-edged and slightly greenish through the helium haze.

Vance checked the hygrometer mounted next to the bunk ladder. Sixty-eight percent. High, but acceptable during blow down. The scrubbers beneath the floor plates hummed with a low, bone-deep thrum that resonated through the heels of their boots. The motors were sealed, three-phase units designed to run without a brush that could throw a spark; a single electrical arc in thirty atmospheres of gas, even with the oxygen dialed down to four percent, was something diving manuals described with words like violent instantaneous deflagration.

He looked down at Thorne. The specialist was watching the oxygen sensor readouts on the primary distribution panel. There were three digital faces, each displaying partial pressure of O2 in millibars. They all read 410, give or take two units.

"They keep it sweet," Vance said. "Two-tenths of an atmosphere above sea level equivalent. Just enough to keep you sharp, not enough to rust your lungs."

"I know the numbers, Vance," Thorne said. His voice was already thinning out, taking on that strange, tinny buzz that made every consonant sound like it was being struck on an anvil. "What’s the pipeline pressure on the export side?"

Vance paused, his hand on the ladder rail. "Sixty bar. The Norwegian line is shut in back to the platform, but the riser still holds fifteen miles of wet gas. Why?"

"Just wondering how much head we’re working under when we crack the sleeve."

"That’s why they brought the hot-tap kit," Vance said. "We don't crack the sleeve until the diverter is set. That was the brief on the deck."

"Briefs are written by men who stay dry," Thorne said. He didn't look up from the gauges. His fingers were long, the nails trimmed straight across, perfectly white at the edges.

Miller turned his head on the bunk. His small, piggy eyes fixed on Thorne’s profile. "You’ve got a lot of questions about the iron for a man who’s down here to run ultrasonic scans."

"The ultrasonic needs a clean surface," Thorne replied without missing a beat. "If the line has structural movement while the collar’s being mounted, the transducer won't calibrate. If the transducer doesn't calibrate, we don't know if the metal's four millimeters thick or fourteen. Then we're all sitting in the bell waiting for the blowout."

Miller watched him for a three-count longer, then grunted and turned back to his red setter. "Fair enough. But don't touch the manifold controls. Keith’s the bellman, I’m lead. You run your little probe and stay out of the dirt."

The pressure whistle continued, steady as a waterfall through an open window.

Vance sat on the lower bunk opposite Lind. His knees were stiffening. He was forty-six, which was fifty-six in saturation years. The constant living at depth, the long weeks breathing gas that dried out your sinuses until your breath tasted like iron filings, the endless cycling of your blood from sea level to the weight of three football fields of water—it ate the cartilage out of your hips. The young ones like Lind didn't feel it yet. Lind moved like an eel, all loose shoulders and easy balance. But Vance knew the ledger. Every day down here was a week taken off the back end of your life, paid for in cash and hard currency by oil companies who didn't give a damn about your joints so long as the crude kept moving south toward the refineries at Grangemouth.

The deck of the Aegir Discoverer was already five atmospheres behind them. Outside the hull, the North Sea was gray and cold, forty-two degrees Fahrenheit of green soup full of herring fry and plastic drift. Inside, it was eighty-four degrees and getting hotter.

"Control," Vance said, leaning toward the horn. "Give us some chiller through the jacket. We’re cooking the bacon down here."

"Copy that, Keith," the supervisor’s voice came back. It sounded tiny now, like an ant shouting through a crack in the wall. The helium speech unscrambler on the surface hadn't been kicked in yet; the topside crew could still understand them, but the divers sounded like ducks to each other. "Cracking the brine coil now. You’re at seventy meters equivalent. Rate of drop is good."

A soft, metallic gurgle moved through the perimeter pipe behind the bunks. Cold brine, pumped from the ship's refrigeration plant, began to circulate through the copper coils wrapped around the outside of the pressure hull. The radiant heat that had been building off the steel frame paused, then began to recede, leaving a sour, damp chill that made Vance’s ribs ache where an old harness buckle had bruised him three seasons ago.

Lind reached under his bunk and dragged out a battered red plastic box with a cracked lid. "Ludo?" he asked, holding up a greasy wooden die.

"Fuck off, Lind," Miller said from the bunk above.

"Keith?"

"I’m reading," Vance said, though the paperback in his pocket was four days old and missing the last twenty pages.

"Mr. Thorne?"

Thorne looked at the little plastic board Lind was holding out. It was scratched, the yellow and green squares faded to gray by successive washings with surgical disinfectant. "I don't play games," Thorne said.

"It’s not a game," Lind said, setting the board on the narrow table that dropped down from the wall on two lengths of brass sash chain. "It’s a test of whether you can avoid killing each other for twenty-eight days. The trick is to see who cheats first. Miller cheats with the blue pieces. He thinks because his fingers are like Cumberland sausages nobody sees him slide the four into the home row."

Miller didn't deny it. He just pulled his blanket up over his shoulders. The wool was rough and smelled of the laundry barge in Lerwick—industrial soap and stale diesel.

The hiss of the gas changed tone, dropping half an octave as the manifold automated the next stage of the injection. They were through the eighty-meter mark now. The air had the distinct, metallic taste of high-purity helium—a strange, dry sensation that made your teeth feel cold when you inhaled through your mouth. Your mouth water went thin; your tea, when it came through the food lock, would go stone cold before you could finish half a mug because helium sucked the heat out of liquid four times faster than air.

Vance stood up again, restlessly pacing the four paces of clear floor between the bunks and the inner airlock door. He peered through the tiny viewing port—a circle of three-inch acrylic no larger than the bottom of an oil drum.

Outside the glass was the transfer trunking: a short, vertical cylinder of steel that connected Chamber One to the diving bell when it was mated to the top hatch, and to the large, six-man wet chamber behind them. Right now, it was empty, dark, and holding the same pressure as their living quarters. A single red indicator light showed that the interlock was set.

Beyond the trunking, somewhere in the bowels of the Aegir, the ship’s main engines throbbed. He could feel them through the soles of his slippers—a tiny, rhythmic twitch, seventy-two beats a minute. The ship was keeping its heading by computer, four azimuth thrusters fighting the easterly chop that was rolling in from Norway.

If the ship lost station—if a thruster failed or the computer had a stroke—the taut-wire system would snap, the bell umbilical would stretch like a licorice string, and the steel tube they were sitting in would become an eight-foot tomb sitting on the deck of an out-of-control five-thousand-ton barge.

He’d seen it happen once, twelve years ago, on the old Stena Seaspread. A diver named Henderson had been out on the pipe when the ship drifted fifty yards to leeward before the dynamic positioning alarm could sound. Henderson hadn't even had time to scream; the umbilical had parted at the hat, and by the time they got the bell down to him, the cold had already done the work. He was stiff as a salt cod by the time they dragged him through the door.

Vance touched the cool glass of the port. It was sweating on the outside, a ring of condensation forming where the warmer chamber air met the unheated trunking.

"Something on your mind, Keith?" Lind asked, setting his four red pegs into their starting holes.

"Just thinking about the flange," Vance said, turning back. "The North Sea has four thousand miles of pipe on the bottom. Why does this one have to be ninety miles from nowhere in the middle of November?"

"Because that’s where the leak is," Lind said reasonably. He rolled the die. It came up a two. He moved one peg out of the paddock. "Fifty thousand barrels a day of condensate going straight into the cod banks. The Ministry’s having kittens. The diver super said the share price dropped six percent before breakfast."

"The share price," Vance spat. "I'll tell my knees about the share price. They'll feel much better."

Thorne had opened his small notebook—a black oilskin thing with graph paper inside—and was writing with a pencil. Diver’s pencils were lead, not ink; ink pens exploded at thirty bar when the air trapped behind the cartridge tried to escape. His handwriting was tiny, like insect tracks, perfectly parallel to the blue grid lines.

"You keep a diary, Thorne?" Miller asked, his face still to the wall.

"Data," Thorne said.

"What data?"

"Compression rates. Temperature differentials. Gas consumption per man." Thorne didn't look up. "If we’re forty minutes late on the dive schedule because the bell’s cold, the company deducts the barge day from the service contractor. That’s my firm."

"You work for the insurers?" Miller turned over now, his elbow propping his grizzled head up. His small eyes were dangerous. Divers hated the insurers more than they hated the company men; an insurer was someone who sat in a warm room in Leadenhall Street and tried to find reasons why your widow shouldn't get the death benefit because your medical had been six days out of date.

"I work for the pipeline consortium," Thorne said smoothly. "My job is to certify the repair. If the repair doesn't meet the specification, the line doesn't open. If the line doesn't open, the loss is sixty million pounds a week. So I write things down."

"Well, write down that the bunks are too short," Miller growled. "And write down that the grub from the galley is pig swill. Tell your consortium that."

Thorne made a small mark on the page, then snapped the book shut with a light thwip. The sound was high and sharp in the thin gas.

"I’ll be sure to include it in the appendix," he said.

Lind chuckled, but Vance didn't. He was watching Thorne’s hands. The man had the steady, bloodless fingers of an instrument technician, but there was a tension in his wrists—a tightness that didn't belong to a man who had spent three tours in saturation. When you live in the can, you learn to let your muscles turn to string. You don't hold tension; if you do, the helium headache gets behind your eyes by day two and doesn't leave until you’re back in the decomp lock three weeks later. Thorne was sitting like a man waiting for a starter's pistol.

"Control," Vance said, leaning over the comms again. "What’s our depth?"

"One hundred ten meters equivalent, Keith," the squawk box replied. "You're halfway down the first leg. Life support is dropping the oxygen mix to eight percent. Watch your heaters."

The hissing shifted again, growing rougher, like coarse gravel being shoveled through a chute. The chamber was darkening slightly as the thick gas scattered the light from the deckhead lamps.

A diver lives in a bottle because his blood cannot handle the shift. At one hundred meters, the water outside was a wall of black iron, three hundred and thirty feet thick, weighing down with ten times the force of the sky in summer. To survive down there, they had to take that weight inside themselves. They had to become the pressure. Every cell, every pocket of gas in the gut, every drop of marrow had to match the sea pound for pound, bar for bar, until the human body was just another part of the Atlantic shelf.

Vance sat back down on his bunk. His head was starting to throb with the dull, persistent ache that always came with the hundred-meter line—the "helium squeeze" that no amount of clean mix could totally eliminate.

"Lind," he said softly.

"Aye?"

"Pass the die."

Lind grinned, his small, white teeth showing behind lips that were already drying out from the gas. "Red or blue, Keith?"

"Give me the green," Vance said. "The blue ones are dirty."

He rolled. A four. He brought his piece out into the lane, right behind Lind’s lead runner.

Above them, through eighty millimeters of boiler-plate steel and sixty feet of salt water, the Aegir Discoverer pitched into the trough of a gray North Sea swell, its thrusters churning the foam into yellow froth, holding them firmly over the darkness below.

By four in the morning, the transition was total. The world of normal air, of nitrogen and pine trees and rain that smelled of earth, was an impossible dream on the far side of thirty atmospheres. At three hundred meters of equivalent depth, the chamber was a dense, alien bath where the laws of daily physics had quietly surrendered.

Keith Vance sat on the edge of his rack and tried to drop a dry cotton swab into the waste bin by his foot. The swab didn’t fall; it drifted down slowly, wobbling through the heavy, hyperbaric atmosphere like a dry leaf falling through a tub of cold oil. The air had mass now. When you waved your hand rapidly in front of your face, you could feel the drag of the gas against the webbing of your fingers, a distinct resistance that demanded effort just to clear a path.

The sound inside the hull had changed too. In thirty bar of helium-oxygen, sound traveled at nearly three times its normal speed, stripping resonance from every impact and leaving only sharp, brittle clicks. When Miller dropped his brass belt buckle on the deck plates, it produced a dry, snapping tink instead of a clang, sounding like a broken teacup hitting linoleum.

"Control, Chamber One," Vance said into the intercom horn. To his own ears, he sounded absurd—a chipmunk gargling dry gravel.

Topside, the digital unscrambler processed his voice, mathematically dragging the shrill upper harmonics back down into the human register before sending it to the life-support supervisor’s console. The response came back down the wire, warm and artificially flattened.

"Go ahead, Keith. You're holding at thirty-one absolute. Rate of descent is zero. Welcome to the bottom, lads."

"Mix is steady?" Vance asked.

"Zero-point-four-two bar O2," the speaker crackled. "Argon negligible. CO2 scrubbing at four hundred parts per million. You’re on the shelf, boys. Get some chow down, then we hold for twelve hours of stabilization."

"Understood," Vance said, and hung the horn on its brass hook.

To survive at three hundred meters, the human body had to be soaked through with the mix. Every tissue, the fatty insulation around the nerves, the fluid inside the eyeballs, had to equalize until it was completely saturated with helium. If they went out to work on the manifold now, they were safe from sudden internal collapses, but they were also utterly imprisoned. To walk out into the sunlight today would take nearly two weeks of decompression. If someone cracked the inner door right now, the four of them wouldn't just bleed; they would boil, their blood turning into instantaneous pink froth as thirty atmospheres of dissolved gas erupted out of solution.

Jonas Lind was curled on his side, his hands trembling slightly as he tried to spread margarine onto a cold ship’s biscuit. The involuntary shaking was the High-Pressure Neurological Syndrome—HPNS—an unavoidable side effect of deep helium saturation. The gas molecules, squeezed tight by the crushing pressure, dissolved into the lipid layers of the nerve membranes, causing tiny electrical misfires throughout the central nervous system. Lind’s fingers fluttered like dry reeds in a ditch.

"Try using both hands, kid," Miller grunted from the top bunk. His legs swung over the rail, thick and hairy, his feet swollen to a purplish dough from the moisture in the deck air. "Or just lick the tub. Saves the biscuit."

Lind swore, a high-pitched piping sound that made him sound like an irate budgerigar. "My knees feel like they’re full of broken glass, Miller. Every time I bend the left one, something grates."

"That’s the helium arthralgia," Miller said, dropping his heavy bulk down to the deck plates with a dull thud that rattled the tin mugs on the food shelf. "The gas displaces the synovial fluid in the joints. It feels like grit because it is grit. Dry friction inside the socket. Shut up and chew your lard."

Across from them, seated on the metal equipment locker, Aris Thorne seemed miraculously exempt from the shakes. His hands, resting flat on his knees, were perfectly motionless. He had removed his coveralls down to a gray sleeveless undershirt, revealing shoulders that were unexpectedly broad for a man with such a scholar's face, though his skin possessed the unnatural, curd-like pallor of someone who spent his life under fluorescent tubes in deep hulls.

Vance watched him closely. "You don't shake, Thorne. Most men get the tremors bad past two-fifty."

Thorne didn't look up immediately. He slowly rubbed the heel of his palm against his thigh, a rhythmic, mechanical gesture. "Tremors are a function of compression rate. If you keep your core temperature down and don't fight the gas, the synapses adapt. It’s simple biology."

"Is it?" Miller interjected, leaning his back against the curved yellow bulkhead. "Funny thing, that. I’ve seen twenty-year vets shake so hard their teeth clicked together like castanets at three hundred meters. But you—an ultrasonic pencil-pusher from the Aberdeen office—you sit there like you’re waiting for a train."

"We all have different tolerances, Miller," Thorne said mildly. "Some men drink whisky without getting a liver ache. Some don't."

The food lock, an eight-inch cylindrical tube welded through the side of the pressure hull, gave a heavy mechanical clunk. A red telltale light switched to green as the valve cycled, equalizing the small chamber with the thirty bars of the living quarters.

Lind stood up, his joints audibly clicking, and turned the heavy bronze wheel of the inner door. He hauled out a long, insulated steel tray containing their breakfast.

The heat inside the chamber had begun to dissipate, replaced by the relentless, invasive cold that always characterized saturation life. Helium possessed a thermal conductivity six times greater than normal air; it drew body heat directly out through the skin pores with horrifying efficiency. Even with the internal ambient temperature held at eighty-five degrees Fahrenheit, the divers felt a permanent, creeping draft. If the chamber temperature dropped even two degrees, their teeth would begin to chatter.

Lind slid the foil covers off the tray. "Oatmeal," he announced, his helium-pinched voice lacking any enthusiasm. "And it’s lukewarm. Topside must have let the thermos sit on the galley counter."

"It’s not cold topside," Vance said, taking a plastic bowl and a plastic spoon. Metal utensils were despised in saturation; they absorbed heat so fast they felt like ice against the lips. "Helium sucks the warmth out of the metal container before Lind can even get the lid off. Eat it fast or it’ll turn into gray glue."

The four men ate in silence, the only sound the soft scraped plastic against plastic and the endless, low-frequency vibration of the environmental scrubbers below the floorboards. The oatmeal tasted of nothing. In hyperbaric helium, human taste buds were dulled, the volatile oils that carried the scent of food failing to vaporize properly in the thick, dense medium. Everything tasted like wet cardboard dipped in warm water.

Vance watched Thorne eat. The surveyor consumed his food with methodical precision, scraping every corner of his plastic tub, chewing twelve times before swallowing, then placing his spoon neatly across the empty rim. He had not touched his mug of tea.

"You're not drinking?" Vance asked.

"Tea raises the heart rate," Thorne replied. "Higher cardiac output increases the rate of gas absorption in the bone marrow. The dive schedule says we lock out to the bell at eighteen hundred hours. I prefer to keep my baseline low."

Miller laughed, a short bark that ended in a squeak. "Listen to him. He talks like an operating manual. You ever actually laid your hands on a three-hundred-meter spool piece, Thorne? Ever had to hold a hydraulic impact wrench with four-knot bottom current trying to rip your flippers off while the North Sea tries to freeze your eyeballs inside your mask?"

Thorne turned his cold gray eyes toward Miller. "I have certified twelve tie-ins and four hyperbaric welds on the Frigg and Statfjord lines. I know precisely what the work entails, Mr. Miller. My job is to verify that the pipeline doesn't rupture again three weeks after you patch it with five-hundred-pound flange clamps. I don't need to swing a sledgehammer to understand the mathematics of structural shear."

"The mathematics of structural shear," Miller mimicked under his breath, shaking his head. "Sweet Jesus. We’ve got an engineer in the can."

"Quiet, Miller," Vance said, his voice flat. He turned to Thorne. "What did the topside scan show on the rupture before we locked down? The briefing on the barge was damn thin, Thorne. They told us a twenty-inch gathering line suffered a catastrophic pressure loss between the manifold and the riser template. That’s an eight-mile section of four-inch-thick steel clad in concrete. A pipe like that doesn't just split because the sea is salty."

Thorne picked up his black oilskin notebook from the small fold-down table, his movements deliberate. He didn't open it, but his thumb traced the perimeter of the binding.

"The initial acoustic profile showed an asymmetric fracture," Thorne said. "Not a burst seam. A burst seam runs along the longitudinal weld, following the manufacturing grain. This fracture is transverse. It cut straight across the wall, perpendicular to the flow."

Miller stopped cleaning his fingernails with the tip of a plastic swizzle stick. His eyes narrowed. "Transverse? On a four-inch wall?"

"That’s what the hydrophone data suggests," Thorne said.

"That’s impossible," Vance said slowly. "A transverse crack on high-tensile export pipe means external force. You’d need an anchor drag from a three-hundred-thousand-ton supertanker to snap a concrete-jacketed line like that, and there hasn't been a ship anchored within fifty miles of the sector during the storm."

"Or an explosive charge," Lind squeaked from his bunk, a nervous half-grin appearing on his face. "Like in the Baltic."

None of the older men laughed. In the tight confines of the chamber, the word explosive had an ugly, leaden weight.

"Don't be an idiot, Lind," Miller growled, though his voice lacked its usual certainty. "The North Sea is full of old junk from forty years of drilling. A dropped drill string from a semi-sub, a crane boom that went overboard ten years ago and drifted along the seabed until the swell dragged it across the line. It happens."

"Whatever caused it," Thorne said smoothly, "the company cannot resume pumping until the integrity of the remaining manifold is certified. If the fracture propagated through the anchor flange, the entire seabed template will have to be abandoned. That would represent a total loss of the field's infrastructure for the next eighteen months."

"And that’s what your little black box tells you?" Vance asked, nodding toward the Pelican case Thorne had brought inside the airlock.

The case was made of thick, dark-gray structural resin with high-impact latches and an automatic purge valve designed to keep it from imploding during the blow-down. It sat beneath Thorne’s bunk like an unexploded mine, secured to the tubular steel frame with two heavy nylon ratchet straps.

"It contains the wide-band ultrasonic array," Thorne said. "It uses phased pulse-echo technology to map the crystalline structure of the metal up to twenty centimeters deep. If there are microscopic stress fractures inside the flange where the eye can’t see them, the scanner displays them in cross-section on the terminal."

"And you have to run it yourself?" Vance asked. "The dive plan says you're scheduled to lock out with Miller on the first run. That leaves me in the bell as dive tender, and Lind on the backup umbilical."

"The instrument requires manual calibration on-site," Thorne said. His voice didn't waver. "The acoustic impedance of high-pressure helium-oxygen mixes distorts the signal if the receiver isn't trimmed by hand on the seabed. It cannot be operated remotely."

Vance didn't answer. He turned his face toward the small, thick viewport that looked out into the transfer trunking.

Beyond the glass, the trunking was dark. In twelve hours, that hatch would swing down, opening the way into the three-man diving bell—the tulip—that would detach from the top of the sat system, drop down through the center of the ship’s hull via the moonpool, and plunge three hundred meters down into the absolute pitch of the ocean floor.

At that depth, there was no sunlight. The water was thirty-five degrees Fahrenheit, bitter and black as ink. The divers would be connected to the bell by thin, eighty-meter umbilicals—bundles of high-pressure hoses that carried their breathing gas, their hot water for their suits, their communication lines, and their low-voltage headlamps. If an umbilical snapped, or if the hot-water pump on the barge failed, a diver had less than five minutes before the cold pulled his core temperature down into cardiac arrest.

And yet, inside the chamber, the danger felt closer.

Vance rubbed his eyes. The helium headache was settling in behind his temples, a dull, throbbing pressure that felt like an iron band being tightened by a quarter-turn every hour. He looked at the Hamilton chronometer on the bulkhead. It was 05:15. Eleven hours until lockout.

"Lind," Vance said.

"Yeah, Keith?"

"Stow the breakfast tray in the lock and cycle the valve. Then get in your rack and sleep. I don't want you on the secondary gas line with your head half-cocked from lack of rest."

"Can’t sleep," Lind mumbled, his voice a reedy hum. "The cold gets into my teeth. Can we get Control to kick the hot brine up a couple of notches?"

"If they kick the brine up, the humidity jumps to ninety percent," Miller said from above, his voice muffled by his wool blanket. "Then we get the skin rot. You want your armpits smelling like old cheese by Tuesday? Leave the temperature alone, Lind. Put your thermal socks on."

Lind grumbled something unintelligible, pulled a heavy fleece beanie down over his ears, and dragged his thin wool blanket up to his chin. Within ten minutes, his breathing slowed, broken occasionally by the small, twitching snorts of HPNS.

Miller was already snoring—a dry, rattling wheeze that sounded peculiarly harmless in the thin gas.

Vance remained seated on the lower bunk, leaning forward with his elbows on his knees, his hands clasped together. Across the narrow center gangway, Thorne was still sitting upright, his back straight against the curve of the steel wall, his hands folded in his lap.

"You should sleep too, Thorne," Vance said quietly, keeping his voice low so as not to wake the others. "The bell is hard work. Even if you're just holding a sensor probe, the seabed takes it out of you. The cold drains you twice as fast as you think."

Thorne looked at him. The green glow of the bulkhead instrumentation cast strange, angular shadows across his cheekbones, hollowing out his eye sockets until he looked like an anatomical diagram.

"I sleep in four-hour intervals, Vance," Thorne said. "The body doesn't require more if the metabolic waste is kept low. How many years have you been in saturation?"

"Twenty-two," Vance said.

"That’s a long time to live under pressure."

"It pays the mortgage," Vance replied, his tone flat. "And once your blood gets used to the mix, you’re not fit for much else anyway. You try working on a building site topside after ten years in the North Sea. The gravity feels wrong. The air feels too heavy, like you're breathing wet wool."

Thorne gave a tiny, dry nod. "A caged animal always finds the open field uncomfortable."

"Is that what we are? Caged animals?"

"We are men who agreed to enter a steel tube under thirty atmospheres of synthetic gas for five hundred pounds a day," Thorne said calmly. "The definition of sanity depends entirely on the observer's balance sheet."

Vance stared at the man. There was something completely detached about Thorne—a lack of the basic nervous camaraderie that usually formed between men crammed into a pipe no wider than a sewer main. Divers were vulgar, noisy, profane men who dealt with the terror of their trade through dark jokes, endless cards, and constant bitching about the food and the company. Thorne had none of that. He was an instrument, cold and self-contained, dropped into their midst from an Aberdeen boardroom.

"Where were you working before this call?" Vance asked.

"Rotterdam," Thorne answered without hesitation. "Structural evaluation of subsea manifold modules for the Dutch sector."

"You came out fast. The rupture only happened three days ago."

"When twenty-inch lines fail, Vance, oil companies move very quickly. Every day the line is shut in, the Dutch and British grids lose twelve million cubic meters of gas. It creates... pressure."

"Yeah," Vance murmured, looking down at his own calloused hands, noticing the slight, almost imperceptible tremor in his left thumb. "Pressure. We’ve got plenty of that."

Thorne closed his eyes, leaning his head back against the insulated rim of the deckhead stringer. His breathing leveled out immediately, becoming slow, shallow, and perfectly regular.

Vance sat in the cold silence of the chamber, watching the red digital numbers of the oxygen sensor tick between 418 and 421 millibars. Outside the steel skin, sixty feet beneath the surging gray waves of the North Sea, the hull of the Aegir Discoverer groaned as its massive thrusters fought the undertow. And three hundred meters straight down through the black water, lying on the ancient mud of the continental shelf, the cracked pipeline waited in the dark.