Read Chapter 9: The Roof Chase

The wind hit them like a fist the moment they breached the roof hatch. Mercer blinked against the grit stinging his eyes, one hand clamped to the metal lip, the other reaching back to steady Camille as she pulled herself up beside him. The train swayed beneath them, a living beast, its roof a long steel canyon of rivets and ventilation cowlings stretching toward the rear where the tunnel darkness swallowed the tail lights.

"There," Camille said, pointing.

A figure moved against the gloom—forty meters ahead, low and fast, weaving between the exhaust stacks. Black coat, compact frame. He carried a silver case in his left hand, pressed against his body like a child he was protecting.

Sokolov.

Mercer dropped into a crouch and moved. The roof sang under his boots, each footfall a dull thunderclap he knew was audible in the carriage below. He didn't care anymore. The man had Vernet. He had the samples. And somewhere under that silver lid was the reason three scientists had vanished in four days.

Sokolov glanced back. Even in the half-light, Mercer caught the flash of recognition—the man he'd fought in the maintenance shaft, the man who'd left him bleeding and empty-handed. Sokolov didn't slow. He turned and sprinted toward the rear coupling, nimble as a cat on a fence line.

"Stop!" Mercer shouted. Useless. The tunnel swallowed his voice.

Camille was already ahead of him, moving with a practiced grace that made Mercer's own footwork feel clumsy. She reached the first gap between carriages and leaped, her silhouette cutting a clean arc against the lights of the car behind. She landed, rolled, came up running.

Mercer followed. The gap between cars was a chasm of black wind, the churning track audible below—a death song if he misjudged. He didn't misjudge. He'd done this crossing a hundred times in training. Normandy. The Scottish viaduct. The bridge outside Lyon where the train had nearly—

The train shuddered. A deep, grinding groan traveled up through the steel like a living thing waking from a bad dream. Mercer stumbled, grabbed a vent cowling, and looked forward.

The tunnel mouth had changed.

No—not changed. The tunnel had closed. A wall of black concrete rushed toward them as the train plunged into a narrower bore, the maintenance spur cut into the chalk bedrock. The clearance dropped from meters to centimeters in a breath.

"Down!" Camille screamed.

Mercer didn't hesitate. He dropped flat against the roof, pressing his body into the shallow channel between two ventilation banks. The air changed. It compressed, pushed down on him like a giant's palm. The train hit the bore entrance and the world became a thunderous roar of enclosed space, the concrete ceiling passing so close he could have touched it if he'd raised a hand.

He didn't raise a hand. He kept his face down and his breath shallow as the maintenance spur swallowed them whole.

---

They lay there for what felt like an hour but was probably ninety seconds. The train slowed, its brakes complaining in long metallic shrieks. The roof stopped vibrating. The grinding eased.

Mercer pushed himself up slowly, ears ringing. The roof lights had changed from the orange glow of the main tunnel to a dim, sickly amber—maintenance lighting, spaced far apart, leaving pools of shadow between.

"Camille."

"I'm here." She was already on her knees, scanning the roof behind them. "He's gone."

Mercer followed her gaze. The rear of the train was empty. Sokolov had either dropped into a gap between carriages or found a ventilation access he knew about. Either way, the silver case had vanished with him.

"One of the vents," Mercer said. "He knows where he's going underground."

"Or he never meant to be seen at all." Camille pulled a small flashlight from her coat and swept the roof in front of her. The beam caught something two meters away, glinting against a seam—metal, thin, shaped like a small pen.

She retrieved it carefully, holding it between two fingers. A syringe. Stainless casing, needle guard retracted, a drop of pale amber liquid beading at the tip.

"Fresh," Camille said. "He dropped it in the chase. Either that or he left it for us."

Mercer took it from her, turning it toward the light. The amber liquid had a faint oily sheen, almost iridescent. The kind of thing that didn't exist in nature.

"Can you analyze it?"

Camille's jaw tightened. A flicker of something—hesitation, calculation—passed across her face before she nodded. "If we're still alive in an hour, yes."

The train lurched. It was moving again, slower now, trundling along the spur with the hesitant gait of a machine navigating unfamiliar ground.

Mercer pocketed the syringe. The weight of it felt like an accusation. "He's heading somewhere specific. The rear of the train doesn't get him anything—the luggage car's forward, Vernet's compartment is mid-train. He was running from us, not toward something."

Camille's eyes narrowed. "Or he established a secondary exit earlier. A cable drop, a maintenance hatch in the tunnel lining."

"A planned extraction."

"That's what I'd do."

Mercer turned toward her fully. The dim amber light carved her features into sharp relief, all angles and shadows. Whatever she was holding back, it was visible now—a guardedness that hadn't been there on the platform in London.

"You'd know, wouldn't you."

Camille went still. "What's that supposed to mean?"

"You recognized his name in the control room. Don't deny it—I saw your face when you read the manifest. You went pale." He took a step closer. "Sokolov. You've worked with him."

"I haven't—"

"Camille. You were on the rooftop before I could see his face. You didn't run at him, you ran around. You were cutting off his route before you even knew he was there."

The silence stretched between them. The train swayed, finding its rhythm on the spur tracks. Below them, faintly, Mercer could hear the murmur of the remaining passengers, unaware of the shadows on their roof.

"I wanted to make sure he couldn't reach the rear," Camille said finally. "That's all."

"Because you knew what he'd do if he got there."

"I knew what he was capable of." She held his gaze for a long moment, then looked away. "There was an operation in Prague. Two years ago. Sokolov was another asset on the network. He went dark, and three of my contacts died before I could extract them. MI6 had someone in the region who could have warned us." Her voice hardened. "The warning never came."

Mercer heard what she didn't say. The accusation was in the pause, in the way her eyes flicked to his face and away again.

"Who was your MI6 contact?"

"You tell me." She reached into her coat and pulled out a folded slip of paper—grease-stained, worn along the creases. She pressed it into his hand. He unfolded it: a name, handwritten, an old-fashioned script he recognized with a cold certainty that settled in his stomach like lead.

*Charles Mercer.*

His father. Dead eight years, head of station Berlin, buried with full honors and an obituary that mentioned none of his true work.

"This was in Sokolov's jacket," Camille said. "He seemed very interested in you. And in what your father knew about a facility in the Scottish Highlands."

The train's brakes engaged. A long, descending whine. They were arriving at the maintenance spur.

Mercer looked from the note to the syringe in his pocket, to the rear of the train where Sokolov had vanished.

The silver container. The biological agent. His father's name in the hands of a freelance killer.

"You should have told me," he said.

Camille's expression was unreadable. "So should you."