Read Chapter 32: The Final Dive

The tunnel mouth was a black circle cut into the concrete, and Anya stood at its edge in her dive rig, a thin figure under the halogen wash of the flotilla's work lights. The makeshift debris screen—old gratings and a welded frame—had been winched aside an hour ago, and the water beyond gave nothing back, no gleam, no current visible. It just waited.

Finn stood at her shoulder, his hands jammed in his coat pockets so she wouldn't see the tremor. The fever had him sweating despite the cold, but he'd made himself useful, hauling cable, checking seals on the air line. The pouch she'd given him was tucked inside his jacket, against his chest, a pressure he could feel with every heartbeat.

"It's a simple valve replacement," she said, not looking at him. Her voice was steady. "The line's marked all the way to the valve chamber. I'm in, I'm out, before the tide turns. Six hours."

"You've said that three times."

"Because you keep looking at me like I'm already dead."

He didn't answer. Beneath them, the maintenance tunnel dropped away into the older levels of the city, the pre-flood London that ran under the walls like a skeleton.

Carver passed Anya the final tool pack and clamped a hand on her shoulder. "Kick the valve for me. I want to hear it."

Anya grinned, thin but real, then stepped off the edge. The splash was small, swallowed by the dark. Her headlamp flicked on, a pale cone that caught silt and drifting plastic. She gave a thumbs-up, then turned and swam into the mouth of the tunnel. The cable behind her paid out smooth and steady.

Finn watched until the light shrank to a mote, then nothing.

Mara had set up a board on the deck of the *Rosie*, with the tunnel schematic Dr. Chen had sketched from memory. Finn stood over it, tracing the line Anya would take—a straight run of four hundred meters, then a dogleg left, then the valve chamber. The secondary lock sat beyond that, ancient steel and rubber that had been holding back the sea for longer than the walls had stood.

"She's at the dogleg," Mara said, tracking the cable line on her gauge. The roller above the tunnel mouth fed back slack foot by foot. "Good pace."

Finn said nothing. The fever was making time stretch and compress. He closed his eyes, counted breaths.

An hour passed in pieces. The cable feed stopped.

"Marker three," Mara called. "She's at the valve chamber."

Relief loosened something in Finn's chest. He leaned over the board, tracing the access points. "Tell her to check the bypass first—the seat's on the far side."

Mara spoke into the wire handset, her voice flat with static. There was a pause, a crackle, then Anya's voice, tinny and far away: "Seat's corroded. Gonna need the pry bar to get the old one out. Give me ten."

Finn watched the minute hand on his watch crawl. When ten minutes passed, the hush on the deck grew thicker. "Anya," Mara called. "Status."

Static.

The cable line twitched once, then ran slack.

"Anya, come back." Mara's voice sharpened.

A burst of static, then Anya's words came through chopped and urgent: "The seal's gone—the door's closing—I can't—"

The line went dead.

Finn was moving before the sound died. He stripped off his jacket, the pouch falling onto the deck boards, and grabbed the spare rig from the locker. Carver was at his elbow, hauling the oxygen tanks, but Finn shook him off and buckled his own.

"You're fever-blind," Mara said, catching his arm. "You dive like this, you're dead."

"If she dies, I'm dead anyway," he said, and pulled away from her. He stepped off the deck and hit the black water.

The cold hit like a fist. His fever burned under it, steam rising off his skin in the glow of his headlamp, and the tunnel mouth swallowed him in three strokes. The cable led him—he followed it hand over hand, silt swirling in the cones of light, passing markers one and two and three. At the dogleg, he saw it: the cable went in, but the tunnel ahead had changed.

A heavy pressure door had slid down, a massive slab of green-pitted steel, stopped halfway and jammed on a fallen chunk of ceiling debris. Beneath it, the gap was barely a meter of black water. The cable vanished under that gap, and faintly, a gloved hand was reaching through, scrabbling.

Anya.

Finn swam to the gap and grabbed her hand. He pulled. She pulled back. Her voice came muffled through the water, desperate against the rush: "Valve took my tool pack—it's wedged—I'm stuck against the far side—"

He went under the slab. The debris pressed his tanks down; he felt the metal scrape along his side and then he was through, into the valve chamber. Anya was pinned between the valve housing and the fallen slab, her arm bent behind a pipe, her rig torn. Blood bloomed dark in the water around her wrist.

He pulled her free. She gasped as the pressure lifted, and he saw her mouth form words he couldn't hear. The slab above them shifted with a groan—and dropped.

The water hammer drove them both down and forward, through a breach in the chamber wall that hadn't been on the schematic, a break into the old service chute beyond. The current caught them, twisted them, and dragged them into a narrow black channel that fell at an angle, tumbling them over pipework and rubble until they slammed into a steel baffle and came to rest in a shallow pocket of air.

Finn surfaced first, gasping. Anya beside him retched water, her lips already blue. The air was thin and tasted of rust. His headlamp cast a weak beam over their cage: a vaulted chamber maybe ten meters long, the ceiling just above them, the water below fed by a current that swirled past and into a grate at the far end.

He checked his oxygen gauge. A quarter tank. Anya's was cracked, empty.

"How long?" she asked, teeth chattering.

"Not enough."

Above the grate, he saw something half-hidden in the silt and scum: a faded plastic chart, the kind used by the old maintenance crews, bolted to the wall. He pulled himself across the water to it and scraped the grime away. The chart showed this tunnel system—but it showed chambers and passages that didn't exist anymore, a city beneath the city. Near the bottom of the chart, in faint red ink, was a hand-drawn circle around a mark he didn't recognize. The symbol looked less like a technical notation and more like a scratched-in gesture. An arrow, pointing down, followed by what could have been a date. Or a number.

"Anya," he said, hoarse. "This chart. It's got something marked on it."

She swam to his side, squinting at the weathered plastic. Her brow furrowed. "That's not on any map I've seen. That mark—" She traced it with a shaking finger. "That's old script. Pre-wall."

The current whispered past them. Somewhere above, the tide was turning, and the seconds were bleeding out of the air.

"It's a riddle," she said quietly. "The old maintenance crews left them. Notes for the ones who followed."

Finn stared at the scratched arrow. The air pocket was already thinning.