Read Chapter 32: The Trade

The cufflink felt like a hot coal between Mercer’s fingers. Remi’s pistol never wavered, its muzzle a black eye staring at him from across the maintenance bay. Dr. Vernet stood between them, her wrists raw from the zip ties, her face pale but her jaw set in quiet fury.

“You’re a businessman, Alex,” Remi said, his voice smooth as polished glass. “You understand leverage. The cufflink for the scientist. A fair trade.”

“You gave Sokolov the vial,” Mercer said. “What’s to stop you from shooting us both the second I hand this over?”

Remi’s smile was thin and reptilian. “Because shooting you would be wasteful. And I am nothing if not efficient. The cufflink contains the formula. The vial contains the weapon. Together, they make me rich beyond any nation-state’s budget. You, Mr. Mercer, are simply in the way.”

Vernet’s eyes met Mercer’s. She gave a barely perceptible shake of her head. *Don’t.* But what choice did he have? The device on the gas line was still ticking down. Camille was somewhere in the tunnels, possibly bleeding, possibly dead. And the train was still coming.

Mercer tossed the cufflink underhand. It arced through the fluorescent light, a small silver glint, and Remi caught it without lowering his weapon. He examined it for a moment, turning it between thumb and forefinger, then pocketed it with a satisfied nod.

“Dr. Vernet,” Remi said, gesturing with the barrel. “You’re free to go. Mr. Mercer has purchased your life with a rather significant currency.”

Vernet stepped toward Mercer, her hands still bound. Mercer reached for her, but Remi’s voice cut through the air.

“One more thing.”

Mercer’s hand froze mid-reach. “You said fair trade.”

“I said the cufflink for the scientist. I didn’t say anything about the toxin.” Remi’s smile widened. “You see, Alex, I’ve realized that selling an antidote is only profitable if there’s a plague. And selling a plague is only profitable if there’s no antidote. Both of those things are true now. The formula is in my pocket. The device is wired to this building’s lungs. And the train—ah, the train.”

He tapped his ear, where a small earpiece glinted. “The train is the delivery system. Not the decoy in the undercroft. Not the gas lines. The train itself. Aerosolized dispersal through the HVAC. Every passenger breathing that beautiful, untraceable compound by the time we hit the Pas-de-Calais.”

Mercer’s stomach dropped. “You rigged the train.”

“I rigged the *air*,” Remi corrected. “The device in the gallery is a distraction—a beautiful, elaborate one that keeps your people busy while the real payload rides the rails. By the time anyone realizes the Palais is safe, the train will be empty of life and full of questions. The commission will be blamed. The cover-up will be exposed. And I will be very, very wealthy.”

Vernet’s breath caught. “The passengers—ninety seconds. Respiratory failure in ninety seconds.”

“Ninety seconds is generous, I think,” Remi said. “Gives them time to realize what’s happening. The panic. The scramble for exits that don’t exist. Sealed tunnel, sealed train. It’s almost poetic.”

Mercer’s mind raced. The gas line device was a fake. The train was the real threat. The cufflink was gone, his only leverage, now in Remi’s pocket. And the train was moving at speed under the Channel, its passengers unaware they were riding a hearse.

“You’ll never get off this train,” Mercer said.

“I’m not on it,” Remi replied. “That’s the beauty of remote detonation. A timer, a signal, a dead man’s switch. The release valve is already installed in the engine compartment. It opens at the half-way point, deep enough under the Channel that no one can evacuate. All I have to do is wait.”

He stepped backward toward the service door, his weapon still trained on them. “Dr. Vernet, I’d suggest you study that gas line device. It may not be the real threat, but it’s still very much active. And you have”—he glanced at his watch—“twenty-two minutes until it floods this entire level with enough natural gas to level the Palais.”

Then he was gone, the door clicking shut behind him.

Mercer’s hands were on Vernet’s bindings before the echo of the door faded. “We need a radio. Camille’s still out there.”

Vernet winced as the plastic cut into her wrists. “The maintenance bay. There’s a service station two corridors left. I saw it when they brought me in.”

They moved fast, Vernet navigating the labyrinthine undercroft with the memory of someone who’d been dragged through it not hours earlier. Mercer’s shoulder throbbed where Sokolov had slammed him into the pipe, but adrenaline burned the pain away. Left, left, through a pair of heavy steel doors, and there—a small alcove cluttered with toolboxes and a battered Motorola radio clipped to a charging dock.

Mercer snatched it, thumbing the channel selector. It was an encrypted frequency, military-grade, the kind used by the Gendarmerie’s special units. But he knew her call sign. He’d heard Sokolov use it in the tunnel.

“Camille. Camille, do you copy?”

Static. Mercer tried again, his voice lower, harder. “Camille, this is Mercer. Respond.”

A crackle. Then, thin and ragged: “Mercer? You’re alive.”

Relief hit him like a wave. “Where are you?”

“Lower utility corridor, level three. Sokolov took a piece of my arm—nothing serious. He bolted when the fire alarm went. I’ve been trying to find a way back to you.” A pause. “What’s happening up there?”

Mercer looked at Vernet, then spoke into the radio. “The gas line device is a decoy. Remi has the real dispersal system on the train. He’s going to vent the toxin into the passenger cabin mid-Channel.”

Silence. Then: “That’s insane. The train’s sealed. They’d never get it past the departure checks.”

“He already did. The engine compartment. He said it’s on a timer—hooks into the existing HVAC.” Mercer’s jaw tightened. “I need you to get to the northbound maintenance access. There’s a service hatch at kilometer marker forty-two that opens into the tunnel’s crisis bay. If we can reach the train before it hits the half-way point, we can get onboard.”

“Onboard a moving Eurostar?”

“Through the engine coupling. It’s a sealed unit, but there’s a maintenance ladder that runs alongside the track. We’d need to match speed, then climb.” Mercer knew how insane it sounded. He also knew it was the only option. “Can you do it?”

Another pause. He could hear her breathing, steady despite the pain. “I’ve done dumber things for less money.”

Vernet grabbed his arm, her voice urgent. “There’s no hatch at kilometer forty-two. The service crew sealed those doors after the January arson attempt. You’d need cutting equipment—and even then, the train passes that point in minutes.”

Mercer’s mind seized on the detail. “When does the timer trigger the release?”

“The half-way point,” Vernet said. “That’s approximately eighteen minutes from now, given the current speed.”

“Then we don’t have time to reach the train from outside.” He looked at Vernet, something clicking into place. “You know this train. You helped design the decoy system on it. Where’s the release valve?”

Vernet’s face went pale. “You’re not thinking of—Mercer, the train is sealed. Internal access only. The passengers are in carriages four through nine. The engine compartment is car one, but it’s separated by a blast door. You can’t get through from the passenger side.”

“I don’t need to get through from the passenger side,” Mercer said. “I need to get to the roof. The engines have external maintenance hatches—safety inspection covers. If I can climb along the carriage tops, I can drop in through the engine bay.”

“You’ll be seen. The CCTV cameras on the platforms—insulated, but the train has external cameras facing the roof.”

“Then I’ll move fast.”

Vernet shook her head. “Even if you get aboard, the release valve is wired to a dead man’s switch. If Remi’s timer doesn’t trigger it, a loss of signal will. The moment he realizes you’re on that train, he’ll trigger it himself.”

“So I don’t give him a chance to realize it.” Mercer turned back to the radio. “Camille, change of plan. There’s a service vehicle depot three klicks north of Sangatte. Can you get there?”

A beat. “Depot? Yes. There’s an access tunnel that runs under the rail lines.”

“Then meet me there. We’re going to chase down a moving train.”

He clipped the radio to his belt and looked at Vernet. The cufflink was gone. The formula was gone. But there was still one thing Remi had underestimated.

Mercer knew the train. He knew its schematics because his mentor, Doucet, had spent six months reviewing Chunnel security just before his death. And somewhere in the back of Mercer’s memory, there was a detail about the engine bay’s secondary ventilation—a detail Remi probably hadn’t considered.

“If the dispersal system is in the HVAC,” Mercer said slowly, “there’s a secondary intake that runs independent of the main system. It feeds fresh air from the front of the train. If I can bypass the main filter and route the cabin air through that intake, the toxin would be pushed out the rear exhaust instead of into the passenger section.”

Vernet’s eyes widened. “That would require accessing the primary air manifold—it’s inside the sealed control console. You’d need the master key.”

“The master key,” Mercer repeated. “The one the train chief carries.”

“Or,” Vernet said, “the override code.”

The cufflink. The code he’d sacrificed. It was gone now, in Remi’s pocket. But there was another copy—the one Doucet had left in his personal effects. The one Mercer had memorized years ago, thinking it was a dead man’s whim.

*M4R5H4LL.*

Mercer closed his eyes, reciting the sequence. Doucet’s final message. Not a code for files—the code for the train’s emergency override system. The one that could manually cycle the air filtration units.

“I know the override,” he said quietly.

Vernet stared at him. “How?”

“Because George Doucet taught it to me before he died. I thought it was about the informant network.” Mercer opened his eyes. “Turns out he was preparing for a day like this.”

Vernet was silent for a moment. Then she nodded. “Then you have a chance. If you can reach the engine bay before the timer trips, and if you can input that code before Remi triggers his dead man’s switch.”

“That’s a lot of ifs.”

“It’s a hope,” she said. “That’s more than we had five minutes ago.”

Mercer pocketed the radio and moved toward the door. “Find the suppression team. Tell them the Palais device is a fake—have them disarm it the slow way, don’t risk a pressure cut that could detonate. And stay safe.”

Vernet caught his arm. “Mercer. The cufflink formula—Remi has it. Even if you stop the train, the weapon still exists. Sokolov has a vial. Remi has an antidote and a dispersal system. You’re stopping one branch of a tree that’s still growing roots.”

“One thing at a time,” Mercer said. He pulled free and started toward the maintenance hatch that led to the surface.

Behind him, Vernet’s voice carried through the dark utility corridor. “You’re a hard man to discourage.”

Mercer didn’t answer. He was already thinking about the rails.