Pressure Lock

• Chapter 1 The Final Blowdown
• Chapter 2 Cold Gas, Thin Voices
• Chapter 3 The Empty Bunk
• Chapter 4 Thirty Atmospheres
• Chapter 5 Severed Umbilical
• Chapter 6 Phantom Echoes
• Chapter 7 A Contaminated Mix
• Chapter 8 Whispers in the Tube
• Chapter 9 Nitrogen Shivers
• Chapter 10 The Medical Lock
• Chapter 11 High-Pressure Nervous Syndrome
• Chapter 12 Missing Tools
• Chapter 13 The Belly of the Beast
• Chapter 14 The Interrogation Seal
• Chapter 15 False Reads
• Chapter 16 The Smell of Burnt Oxygen
• Chapter 17 Three Men Standing
• Chapter 18 Bleeding Valve
• Chapter 19 Panic at Ten Meters
• Chapter 20 Dark Current
• Chapter 21 The Logbook Lie
• Chapter 22 Squeeze Factor
• Chapter 23 The Outer Hatch
• Chapter 24 Explosive Decompression
• Chapter 25 Surface Tension
• Chapter 26 Atmospheric Zero

The human body is mostly water, which means it does not compress easily. It simply endures the weight until the atmosphere around it turns thick as soup and cold enough to steal the marrow from your bones.

Sam Burke sat on the edge of the lower aluminum bunk, his heels resting against the wet, patterned rubber of the deck plating. The air in Chamber One smelled of ozone, scorched machine oil, and the sour tang of four men who hadn't breathed unfiltered outside air in twenty-one days. Every breath felt heavy in the lungs, like dragging damp wool through a straw.

"Watch your ears, boys," Shaw muttered, not looking up from his battered paperback. His voice was already shifting into the absurd, squeaky register that helium forced upon vocal cords—a Donald Duck timbre that made every serious statement sound like a vaudeville routine. "Here comes the drop."

A violent hiss tore through the pipework overhead. The blowdown had begun.

High-pressure gas rushed through the intake valves, howling against the curved steel shell of the saturation spread. The chamber—an eight-foot-diameter cylinder bolted securely to the deck of the Aegir Endeavor—groaned under the load. Outside, eighty miles northeast of the Shetland Islands, the North Sea was running an eight-foot swell that rolled the vessel in long, rhythmic sickening arcs. Inside, the motion was muffled, transformed into a continuous, grinding vibration that vibrated directly into Burke’s teeth.

Across the narrow aisle, Julian Vance braced both palms against the upper bunk support. Vance was the team’s lead diver, a veteran of the Norwegian fields who moved with the deliberate, slow economy of an old predator. His knuckles were white against the unpainted alloy. He had a towel draped over his neck, soaking up the sudden burst of condensation that bloomed across every surface whenever the valves opened wide. The temperature in the chamber spiked instantly as the gas compressed, jumping ten degrees in less than twenty seconds.

"Tell topside to ease back on the bleed," Vance said, his voice whistling through his teeth. "Lars, ring the desk."

Lars Lindstrom, curled awkwardly on the far side of the transfer lock hatchway, didn't move immediately. He was staring at the steel floor plates between his feet. His blond hair was glued to his forehead with sweat, and his pale skin had taken on a gray, chalky undertone.

"Lars," Vance barked.

"They have the profile," Lindstrom whispered, though in the helium register it sounded more like a panicked bird. "They aren't going to slow it down for our comfort, Julian. The weather's turning up there. They want us at surface storage before the blow gets worse."

"They'll blow a seal if they slam us through twenty bar that fast," Vance growled.

Burke leaned forward, resting his elbows on his knees. His ears popped with a sharp, needle-like pain, and he swallowed hard three times to clear the Eustachian tubes. "The seals are rated for thirty-five, Julian. Let them pump. The sooner we start the twelve-day clock, the sooner we walk onto the quayside in Peterhead."

"Twelve days," Shaw said with a dry, humorless chuckle from behind his book. "Twelve days in a tin can smelling your socks, Burke. Don't make it sound like a holiday."

The Aegir Endeavor had just wrapped up a three-week intervention on the Heather Field manifold at a working depth of one hundred and eighty meters. They had spent those weeks living in this tube, stepping into the diving bell twice a day to drop into the black, freezing abyss of the sea floor, burning through hydraulic bolts, clearing silt from riser bases, and surviving on reconstituted stew pushed through a double-valved airlock.

Now the bell was lashed to the gantry outside, washed down and salted over. Their job on the bottom was done. But returning to the surface was not a matter of simply riding an elevator up. At six hundred feet of sea depth, their tissues were completely saturated with helium and oxygen. If the chamber hatch were cracked open right now, the gas dissolved in their blood would instantly effervesce like warm soda, tearing every blood vessel, joint, and organ to ribbons within seconds.

To survive the climb back to one atmosphere, they had to sit right here. They had to breathe, sleep, eat, and wait while the automated control consoles on the dive bridge slowly bled the pressure off, half a meter of equivalent depth per hour, for twelve unbroken days.

The hiss of the intake throttled down slightly, the roaring wall of sound settling into a steady, throbbing drone.

Burke reached up to the magnetic whiteboard stuck to the bulkhead above his bunk and tapped the black marker hanging from its string. "Where’s Ethan?"

The question dropped into the cramped space like a lead sinker.

The four men looked at each other. The saturation spread consisted of three linked spheres: Chamber One, which served as their sleeping quarters with its four stacked bunks; the central wet pot and sanitation module, where the toilet and wash basin were; and Chamber Two, currently rigged for gear storage and spare gas scrubbing.

"He went through to the wet pot before the blowdown started," Shaw said, finally lowering his book. His thick, bearded face settled into a frown. "He said he left his logbook in the dry-suit locker."

"The door's dogged," Lindstrom noted, pointing toward the heavy circular steel hatch that separated Chamber One from the wet pot.

The heavy, dog-leg locking wheel on the circular hatch was turned fully home. A thick bead of moisture ran down the cold steel rim.

Vance pushed himself off the bunk and took the two steps required to cross the chamber. He rapped his knuckles hard against the inspection port—a five-inch-thick disc of acrylic set into the center of the steel hatch. "Ethan. Blowdown’s stabilizing. Get your ass in here so we can seal down the inner compartment."

No answer came through the heavy steel. The hatch was insulated against sound and heat, but at three hundred pounds per square inch of ambient pressure, metal conducted vibration with startling clarity.

Vance leaned his forehead against the viewport, cupping his hands around his eyes to block out the harsh fluorescent glare of the bunk room.

The light inside the wet pot was dimmer, lit only by a single amber emergency strip. The floor of that compartment was lower, grating set over the sump where dive suits dripped after a bell run.

"See him?" Burke asked, standing up. The air was thick enough that moving quickly made him feel slightly breathless—an illusion born of gas density that every saturation diver knew well.

Vance didn't answer right away. His shoulders went rigid beneath his faded company-issue sweatshirt. He didn't blink. He pressed his face harder against the thick acrylic, his breath fogging the small circle of glass until he wiped it away with a sudden, violent swipe of his sleeve.

"Julian?" Lindstrom asked, his voice cracking upward in pitch.

"Something’s wrong," Vance said quietly.

Shaw was on his feet instantly, dropping the paperback onto the bunk. "What do you mean, wrong? Did he pass out from the heat?"

"Get the comms," Vance ordered, his voice dropping into the flat, razor-sharp register of a man who had seen too many subsea disasters. "Burke, hit the intercom for Dive Control. Now."

Burke lunged across the small footprint of the chamber, smashing the red push-to-talk button beside the medical lock.

"Dive Control, Chamber One," Burke barked into the brass speaker grille. "We need eyes on Chamber Three and the wet pot. Who’s running the board?"

Static crackled over the intercom, followed by the dry Scottish voice of Dave Miller, the night life-support technician. "Read you, Chamber One. Gas mix is holding at eighty-six fourteen Heliox. What's the trouble, Sam?"

"We need you to look at the CCTV in the wet pot," Burke said, staring at Vance’s back. "Ethan is in there. He’s not responding to the hatch knock."

"Hold one," Miller replied from the safety of the control room four decks above, where coffee was hot, air was thin, and the atmosphere sat comfortably at sea level. A pause dragged out over three seconds, four, five. "Chamber One, camera two in the wet pot is showing offline. Just static. Must've lost the feed during the blowdown surge. Hang on, let me cycle the circuit breaker."

"Don't wait for the camera," Vance said. He reached for the heavy brass dogging wheel on the hatch. "I'm cracking the seal."

"Wait!" Lindstrom shouted, stepping forward with his hands out. "If the pressure isn't equalized between the pots—"

"The equalizer valve is centered, look at the needle," Shaw interrupted, pointing to the twin-faced differential gauge mounted next to the frame. "Both pots are at identical depth. Crack it, Julian."

Vance hauled down on the wheel. The heavy brass teeth engaged with a dry, mechanical clatter. With a sharp grunt, he hauled the lever over center. The rubber gasket gave way with a wet shluck, and the heavy steel door swung inward into Chamber One.

A wall of cold, foul-smelling gas rolled out from the darkened interior of the wet pot.

It didn't smell like Heliox. It smelled like warm copper and ruptured neoprene.

Burke reached past Vance and flipped the toggle switch for the overhead floodlights in the wet pot. The twin halogen tubes flickered twice, then blazed to life, casting a harsh, unsparing white light over the steel decking.

Ethan Harris was not standing by the lockers.

He was wedged between the stainless-steel ladder and the secondary umbilical rack, his body twisted at an unnatural angle. His legs were splayed out across the wet grating, one boot missing entirely. His saturation helmet, an expensive carbon-fiber Kirby Morgan, lay on its side near the floor drain, its clear faceplate smashed into spiderweb fractures.

"Jesus Christ," Shaw breathed, stumbling back a half-step until his spine hit the bunk rail.

Vance dropped to his knees on the grating, lunging into the wet pot. "Ethan!"

Burke followed immediately, having to duck low to clear the circular hatch frame. The metal deck was slick beneath his socks. He dropped beside Vance, his hands instinctively reaching for the carotid artery on the side of Harris’s neck.

The skin was already cooling, cooling with that impossible, terrifying speed that happens when the environment around you is ninety percent helium—a gas that strips heat out of human flesh six times faster than standard air.

There was no pulse.

"He's gone," Burke said, his voice completely level despite the thunder of his own heart against his ribs. Saturation divers learned early that panic consumed oxygen you couldn't afford to waste. "Julian. He's dead."

"He can't be," Lindstrom choked out from the doorway of Chamber One, his face dead white as he gripped both sides of the hatch ring. "We were just talking to him twenty minutes ago. He was talking about his daughter's birthday."

Vance did not pull back. He gripped Harris by the shoulders, turning the younger diver’s torso slightly toward the light.

That was when the light caught the dark, viscous smear across the back of the diver’s skull.

The bone behind Harris's left ear was crushed inward, a neat, crescent-shaped depression that had splintered the scalp and left a thick crust of drying crimson against his collar. It was not the kind of wound caused by a fall against flat decking or a bumped bulkhead. It was the precise, devastating signature of a heavy impact from a curved steel object.

Nearby, resting half-hidden beneath the lowest rung of the gear rack, lay a twenty-four-inch forged steel flange wrench. Its jaws were dark and wet.

The chamber fell dead silent, save for the rhythmic, mechanical hiss of the scrubber fans pushing Heliox through the soda-lime canisters overhead.

"That wasn't a fall," Burke said, looking up at Vance.

Vance looked down at the heavy wrench, then slowly raised his eyes to meet Burke’s. His expression was completely blank, stripped of emotion by thirty years of dealing with subsea emergencies, but his eyes were wide and cold.

"No," Vance said, his high-pitched helium voice sounding grotesque against the grim reality of the metal floor. "It wasn't a fall."

From the ceiling speaker, Dave Miller’s tinny voice crackled down from the world above. "Chamber One, this is Control. We got the CCTV breaker reset, but we're seeing some kind of obstruction on the lens. What's the status on Ethan? Is he out cold?"

Vance stood up slowly, his tall frame bent beneath the low curve of the ceiling. He stepped back through the hatch into Chamber One, standing directly in the center of the narrow aisle.

Burke stepped through behind him, his socks stained with grease and dark fluid from the floor grating.

Lindstrom had backed away until he was pressed flat against the far wall of his bunk, staring in unadulterated horror at the red smear on Burke's feet. Shaw remained standing near the medical lock, his hands hanging loose at his sides, his breath coming in short, audible hitches.

Four men had walked into this system six hours ago after their final dive.

Five men, counting Harris.

The outer doors were dogs-locked, pressurized to eighteen atmospheres, and bolted to a three-thousand-ton vessel drifting in the North Sea. The only access to the outside world was through a six-inch medical airlock designed for sliding soup trays and medicine bottles through a double seal.

No one had come in from the outside.

No one could get out for twelve days.

"Miller," Vance said, leaning toward the intercom, his hand steady as he pressed the talk switch.

"Go ahead, Julian," the speaker returned cheerfully. "We're ready to set the automated decompression profile. First stage takes you from one-eighty down to one-sixty by morning."

Vance looked at Shaw. Then he looked at Lindstrom. Finally, his eyes settled on Burke.

"Hold the profile, Dave," Vance said into the brass grille. "Ethan Harris is dead."

A long silence hung on the line, long enough that the faint hiss of the ship’s electrical grounding hummed through the wire.

"Say again, Chamber One? We have bad comms on your channel. Did you say Ethan is injured?"

"I said he's dead," Vance repeated, his voice utterly devoid of inflection. "And tell the Captain to secure the logbooks on the bridge. We have a murder in the tube."

The silence that followed Julian Vance’s declaration was not the peaceful quiet of an empty room. It was the heavy, suffocating silence of a steel tomb buried under three hundred pounds of pressure per square inch. The air itself felt thick enough to hold a shape, a soup of helium and oxygen that vibrated with the low-frequency hum of the ship’s scrubbers.

Over the intercom speaker, the faint sounds of the Aegir Endeavor’s control room drifted down like transmission signals from a distant planet. They could hear the clink of a ceramic coffee mug against a console, the rhythmic clicking of a printer, and finally, the sharp, ragged intake of Dave Miller’s breath as the reality of Vance’s words cut through the static.

"Chamber One, say again," Miller’s voice came back, stripped of its professional calm. "Did you say... murder? Julian, look, if this is some kind of sick blowout joke to mess with the green hats on the night shift—"

"It’s no joke, Dave," Vance said. His voice was pitched high by the helium, a comical squeak that contrasted horribly with the grim set of his jaw. He kept his eyes locked on the three men standing in the cramped cabin with him. "Ethan is on the deck of the wet pot. His skull is crushed. There’s a twenty-four-inch flange wrench sitting right next to him covered in blood. Nobody fell on a wrench and did that to themselves. Do you copy me? Call the superintendent. Call the captain. Get them to the desk now."

"Jesus... Jesus Christ," Miller muttered. They heard the frantic scrape of a rolling chair being flung backward against a metal bulkhead, followed by the muffled shouting of orders through an open doorway in the dive office above.

Burke slowly leaned back against the edge of his bunk, his heart hammering a frantic rhythm against his ribs. He looked down at his socks. A dark, oily smudge of blood and condensation had soaked through the grey wool of his left foot. He resisted the urge to rub it against the floor plates. In this space, every movement was watched, every gesture magnified by the sheer lack of room.

The chamber was a cylinder eight feet in diameter and twelve feet long. Packed into that space were four aluminum bunks, a narrow aisle barely wide enough for two men to pass shoulder-to-shoulder, and the towering presence of their collective panic.

"We shouldn't touch anything," Lars Lindstrom whispered. He was still pressed flat against his bunk, his fingers hooked into the blue canvas of his mattress as if the ship were listing forty-five degrees. His eyes were darting from Vance’s face to Burke’s feet, then over to Shaw, who had remained frozen near the medical lock. "If it's... if someone... we have to keep the door shut. We have to isolate the wet pot."

"The wet pot is our only way to the sanitation block, Lars," Shaw said. His voice was flat, but there was a tremor in his thick shoulders. He was a broad-built Scotsman with a beard that usually carried a trace of dry humor, but now his face looked like it had been carved from grey shale. "What do you propose we do? Hold our bladders for the next twelve days while we decompress?"

"We have to preserve the scene," Lindstrom insisted, his voice rising in pitch until it was almost a whistle. "That's what they do on the surface. You don't touch anything. You don't move the body. You wait for the police."

"The police are eighty miles away in Aberdeen, you idiot," Shaw snapped, taking a step toward the center of the aisle. "And even if they flew a team out by helicopter right now, how do you think they're going to get in here? They can't just open the hatch. If they crack that seal, our blood will boil before they can ask for our names. We are twelve days from one atmosphere. Twelve days! Nobody is coming through that door to help us."

The brutal reality of their situation settled over them like a physical weight. Saturation diving was an exercise in absolute isolation. They were closer to the vacuum of space than they were to the normal life of the Scottish coast. The steel walls of the chamber were a boundary line between life and instant, explosive death. The pressure inside was eighteen times that of the air outside. To the rest of the world, they were already in another dimension, locked behind three-inch-thick steel hatches that could only be opened after a agonizingly slow, calculated reduction of pressure.

The intercom crackled again, and a new voice cut through the hum. It was dry, authoritative, and laced with the hard edge of a man used to managing disasters. Alistair MacCready, the dive superintendent, was now on the mic.

"Chamber One, this is MacCready. Julian, I’m looking at the chamber telemetry now. Your heart rates are spiking across the board. Tell me exactly what you see in the wet pot."

Vance reached for the brass intercom plate, holding the button down with a thumb that trembled slightly. "MacCready, Ethan is dead. He’s wedged behind the gear rack. He’s got a massive depressed fracture on the left side of his skull. The carbon-fiber shell of his personal helmet is cracked open next to him. And there’s a heavy-duty flange wrench on the deck with tissue on the handle."

A long pause came from the surface. "Is there any chance of resuscitation? Did you check the carotid? Did you try the defib?"

"There's no pulse, Alistair," Burke called out, leaning toward the speaker. "The body is already cold. With the helium mix in here, his core temp is dropping fast. He's been dead at least thirty minutes, maybe longer. We were running the final blowdown, and the noise from the intake valves drowned out whatever happened in there."

"And the wrench?" MacCready asked, his voice dropping into a register of grim calculation. "Where did it come from?"

"It's from the emergency tool kit in Chamber Two," Shaw said, his voice tight. "The tool roll was supposed to be secured under the spare scrubber unit. Someone had to go in there, unbuckle the canvas, and pull the heavy steel flange wrench out."

The four men looked at each other again. The realization was a slow-burning poison. Chamber Two was accessed through a hatch on the opposite side of their sleeping quarters. To get the tool, whoever did this had to walk right past the other bunks, retrieve the weapon, wait for the deafening roar of the blowdown gas to mask the sound of the blow, and then corner Ethan in the wet pot.

And there were only four of them left alive in the system.

"One of us," Lindstrom muttered, his blue eyes wide as he stared at the floor. "One of us did it. We were all in here. We were all supposed to be sleeping or resting before the dive bridge started the clock."

"I was asleep," Shaw said instantly, his face hardening as he glared at Lindstrom. "I had my curtains drawn. I didn't see anyone leave."

"The curtains don't block sound, Shaw," Lindstrom said, his voice trembling. "But with the blowdown gas rushing through the pipes, you could have walked a brass band through here and nobody would have heard it. The noise was ninety decibels easily."

"Are you accusing me, Lars?" Shaw stepped forward, his massive frame filling the narrow space between the bunks. "Because if you want to start throwing names around, let's talk about who was complaining about Ethan's rigging work on the manifold yesterday. You two almost came to blows in the bell because he dropped that hydraulic torque tool."

"That was work!" Lindstrom cried, his squeaky voice cracking. "That was just an argument! I didn't... I wouldn't use a wrench on a man's head!"

"Enough!" Vance barked. The authority in the lead diver's voice was absolute, forged over decades of managing high-stress subsea operations. He stood between the two men, his hands raised to keep them apart. "Shut your mouths. Both of you. We are in a sealed environment under eighteen bar of pressure. If we start fighting in here, we’ll damage the scrubbers or break a gas line, and we’ll all be dead before the ship can even turn around for port. Do you understand me?"

Neither man answered, but they both stepped back, their breathing heavy and shallow in the dense atmosphere.

Over the speaker, MacCready's voice returned. "Chamber One, listen to me carefully. We are contacting the police in Aberdeen and the marine accident investigators. But as you know, they cannot get to you. You are in a mandatory decompression profile. If we stop the decompression, you stay at depth. If we speed it up, you die. The physical laws of saturation are absolute. You have two hundred and eighty-eight hours of decompression remaining before we can open that outer hatch."

Two hundred and eighty-eight hours. Twelve days.

"We cannot send anyone down to assist you," MacCready continued, his voice heavy with the weight of the decision. "And we cannot pull Ethan out without compromising the seal. The medical lock is too small for a body. You are going to have to manage this internally until we can get you down to one atmosphere."

"Manage it?" Burke asked, a cold laugh escaping his throat. "How do you expect us to manage a murder investigation while we’re breathing Heliox in a tin can, Alistair? We have a dead man in the wet pot and a killer sitting on one of these four bunks."

"I know, Sam," MacCready said quietly. "I know. But right now, your primary objective is survival. If the carbon dioxide levels rise because you're panicking and breathing too hard, you’ll black out. If the temperature drops, you’ll get hypothermia. I need you all to sit down, calm your breathing, and let us figure out the safety protocol."

"We need to secure the body," Vance said. He looked back through the open hatch of the wet pot, where Ethan's boots were still visible under the dim orange light. "We can't leave him on the deck. The wet pot has a bilge sump, but the humidity is ninety percent. If we leave him there, the decomposition... the smell will contaminate the entire loop within twenty-four hours. The scrubbers aren't designed to handle organic decay gases."

The medical reality was simple and horrifying. In a closed-loop breathing system, every breath they exhaled was scrubbed of carbon dioxide by passing through canisters of soda-lime, then mixed with fresh oxygen and returned to the chambers. If a body began to decay in the system, the gases produced—ammonia, hydrogen sulfide, and methane—would be pulled into the recirculation loop, poisoning the very air they needed to survive.

"We're looking at the system layout now," MacCready said from the surface. "Chamber Two is currently used for gear storage. Can you clear the lower bunks in there and move him in? If we shut down the heating loop to Chamber Two, we can drop the temperature in that compartment to near freezing. The ambient North Sea water outside the hull will act as a natural refrigerator. That will preserve the body and isolate the smell."

"We can do that," Vance agreed, though his face looked pale at the prospect of moving their dead teammate through the narrow hatches. "But we'll have to move the spare gas bottles and the dry suits into Chamber One. It's going to make our quarters even more cramped."

"We'll manage," Burke said. He looked at the open hatch to the wet pot. "But we need to document the injuries first. Once we move him, the evidence will be disturbed. Alistair, is the camera in the wet pot still showing static?"

"Yes," Miller’s voice broke in. "The lens is completely obscured. It looks like someone smeared grease or a piece of neoprene directly over the camera port before the blowdown. It was deliberate, Sam. Whoever did this didn't want us seeing it on the monitors."

"So the killer planned it," Burke said, his voice dropping. He looked at Shaw, then at Lindstrom, and finally at Vance. "They knew the CCTV layout, they knew the blowdown schedule, and they knew exactly where the emergency tools were kept."

"We all knew that," Shaw muttered, leaning his head against the steel bulkhead. "Every one of us has been living in this rig for three weeks. There are no secrets in a saturation spread."

"Let's get the camera cleaned first," Vance said. He reached into his pocket and pulled out a small microfiber cloth he used for cleaning his dive mask. "Sam, come with me into the wet pot. We need to clear that lens so topside can see what we're doing. Shaw, Lars, stay in Chamber One. Don't touch anything, and don't move from your bunks."

Burke nodded, swallowing down the dry taste of fear that had settled at the back of his throat. He followed Vance through the circular hatch into the chilly, damp air of the wet pot.

The temperature here was already dropping as the ship’s technicians began adjusting the environmental controls. The smell of copper and wet rubber was stronger now, a heavy, metallic tang that clung to the back of the tongue. Ethan Harris lay exactly as they had found him, his body twisted like a broken doll against the steel ladder.

Burke avoided looking at the young diver's face. He had known Ethan for three years; they had worked together on the Forties pipeline, shared beers in the pubs of Aberdeen, and talked about their families during the long, boring hours of decompression on previous jobs. To see him now, reduced to a piece of physical evidence in a freezing metal tube, was a blow that Burke had to partition off in his mind if he wanted to stay functional.

"The camera is up there," Vance said, pointing to a small, pressure-resistant housing mounted in the upper corner of the ceiling dome.

Burke climbed onto the lower rung of the gear rack, careful not to let his feet slip on the wet grating. He reached up to the small acrylic port of the camera housing. His fingers came away wet with a thick, black substance.

"It's high-pressure silicone grease," Burke said, holding his fingers down so Vance could see. "The heavy waterproof stuff we use for lubricating the hatch gaskets. It's kept in the maintenance locker in Chamber One."

"So he took the grease, blackened the lens, went to Chamber Two for the wrench, and then waited in here for Ethan," Vance reconstructed the timeline in a low, squeaking whisper. "It’s cold-blooded, Sam. This wasn't a sudden fight. It was an execution."

"Why?" Burke asked, his voice barely audible over the hum of the ventilation. "What did Ethan have on any of us that was worth killing him for? We’re a team. We’ve been through three weeks of deep dives together."

"I don't know," Vance said, his eyes fixed on the dead man. "But we have twelve days to find out. And we’re locked in here with the man who did it."

Burke wiped the silicone grease off the camera lens with the cloth, rubbing the acrylic until the clear glass showed through. Almost immediately, the small red LED on the side of the housing began to blink, indicating that the signal had been restored to the dive bridge.

"We have picture," MacCready’s voice came through the wet pot's local speaker. "Good job, Sam. Now, we need you to help us document the scene. We're going to take high-resolution screenshots from our end. Julian, I need you to use the digital camera from the medical kit to take close-up shots of the wound and the wrench before you move him."

"Understood," Vance said. He stepped back through the hatch to retrieve the camera from the medical lock in Chamber One.

Left alone in the wet pot with the body, Burke felt the walls of the chamber closing in on him. The steel plating around him was only an inch thick, but it felt like a mountain of lead. Outside that steel was the cold, black water of the North Sea, hundreds of feet of it, pressing down with indifferent, crushing force. Inside was a different kind of pressure—the psychological weight of knowing that one of his remaining crewmates was a monster.

He looked down at the wrench. It was a massive piece of steel, designed for tightening the heavy bolts on high-pressure subsea flanges. It was heavy enough to crack a skull with a single blow, even through the thick neoprene hood of a dive suit.

As Burke stared at the weapon, he noticed something odd about the way Ethan's body was positioned. The young diver's right hand was tucked beneath his chest, his fingers clenched into a tight fist.

Burke glanced up at the security camera. Its lens was pointed directly at him, but the angle was high, and his own body was blocking the view of the deck where Ethan lay.

Slowly, deliberately, Burke knelt down beside the body. He reached out and gently took hold of Ethan's cold, stiffening hand. The fingers were rigid, locked in the early stages of rigor mortis, which was accelerated by the high oxygen content of their breathing gas.

With a firm, steady pressure, Burke pried the fingers open.

Lying in the palm of Ethan’s hand was a small, crumpled piece of yellow waterproof paper—a leaf torn from a diver’s subsea tally book. The paper was wet, but the synthetic material was designed to withstand water, grease, and extreme pressure.

Burke could see dark blue ink smeared across the surface, written in the hurried, shaky hand of a man who knew his time was running out.

Before he could read the words, he heard Vance's heavy footsteps returning through the hatch.

With a swift, practiced motion, Burke slipped the yellow paper into the pocket of his sweatshirt, patted the pocket flat, and stood up just as Vance stepped back into the wet pot with the camera in his hand.

"They're ready for the shots," Vance said, his eyes scanning the space. He didn't seem to notice the slight tremor in Burke’s hand. "Let's get this done, Sam. The sooner we move him, the sooner we can lock that hatch and try to get some air we can actually breathe without smelling this."

"Yeah," Burke said, his heart hammering against his ribs as his fingers brushed the small piece of paper through the fabric of his pocket. "Let's get him out of here."