In the heart of London – Surveillance at a glance…

He edged along the narrow maintenance ledge, gripping the metal rail with white knuckles. The train bucked violently, threatening to throw him into the tunnel wall.

Sparks rained down from the overhead line.

Emma’s voice was steady but strained. “You’re almost there. Keep going.”

Jake reached the coupling between the first and second carriages. The metal beneath him vibrated like a living thing.

He dropped to his knees, reached under the chassis — and found the brake linkage.

A thick steel lever. Manual override.

He pulled.

Nothing.

Emma’s voice sharpened. “Jake — you need to disengage the safety lock first. It’s a red latch.”

Jake felt around blindly, fingers scraping metal until—

There.

He yanked the latch.

The lever moved.

The train screamed — a sound like metal tearing itself apart.

Emma shouted in his ear. “It’s working! Keep pulling!”

Jake put his entire weight into it.

The lever slammed down.

The brakes engaged.

The train shuddered violently, sparks erupting in a blinding cascade. Jake clung to the rail as the world became a blur of noise and fire.

The train slowed.

Slowed.

Slowed—

And finally screeched to a grinding, agonising halt.

Silence.

Then Emma’s voice, breathless:

“Jake… you did it.”

Jake collapsed onto the ledge, chest heaving. “Tell me… we’re not doing that again.”

Emma laughed — shaky, relieved. “No promises.”

But the victory is short‑lived.

Because as the train powers down, the bomb in Carriage Four lights up again.

A new message on the display:

“PRIMARY DEVICE ARMED. 00:59:58.”

A one‑hour countdown.

And the Architect’s voice returns:

“You saved the passengers. Good. Now save the city.”

The train sat dead on the tracks, emergency lights flickering. Passengers were being evacuated through the rear carriages, escorted by transit police who had no idea how close they’d come to catastrophe.

Jake and Emma stood over the bomb in Carriage Four, the timer glowing like a heartbeat.

00:59:12

Emma swallowed hard. “He’s giving us an hour. That’s not mercy — that’s choreography.”

Jake nodded. “He wants us moving. Wants us chasing.”

Emma tapped her tablet. “I’m pulling the transmitter logs. If this device is the key, the primary bomb must be listening for a specific activation signal.”

Jake zipped the duffel shut. “Then we track the signal.”

Emma’s fingers flew across the screen. “I can isolate the frequency… but the Architect is bouncing it through multiple relays. It’s like trying to follow a whisper in a hurricane.”

Jake’s jaw tightened. “We need help.”

Emma looked up. “From who?”

Jake hesitated — then said the name he’d been avoiding.

“From the one person who knows MI5’s blind spots better than anyone.”

Emma’s eyes widened. “No. Jake, she’s not cleared. She’s not even—”

“She’s the best cryptographer we’ve ever had,” Jake said. “And she didn’t leave MI5. She was pushed out.”

Emma exhaled. “Tess.”

Jake nodded once. “We need her.”

Tess Calder lived in a converted warehouse in Shoreditch — a fortress of screens, servers, and half‑assembled drones. When Jake and Emma arrived, she was already at the door, arms crossed, expression unimpressed.

“You two look like you’ve been chewed up by the Underground,” she said. “What did you break this time?”

Jake didn’t waste a second. “We need you to trace a signal. High‑level encryption. Architect‑grade.”

Tess’s smirk vanished. “The Architect? You’re joking.”

Emma shook her head. “We have less than an hour.”

Tess stepped aside. “Then get in here.”

Inside, her workspace was a controlled chaos of cables and glowing monitors. Tess slid into her chair and held out her hand. “Give me the device.”

Jake placed the bomb’s transmitter module on her desk — carefully.

Tess raised an eyebrow. “You brought me a live bomb. How thoughtful.”

Emma crossed her arms. “Can you trace it or not?”

Tess cracked her knuckles. “Watch me.”

She connected the module to her system. Lines of code streamed across the screens. Tess’s eyes darted, tracking patterns only she could see.

“Okay… okay… he’s good. Very good. He’s bouncing the signal through dark fibre, piggybacking on dormant infrastructure. This is old Cold War tech.”

Jake leaned in. “Can you find the endpoint?”

Tess smirked. “Already did.”

She tapped a key.

A map appeared.

London.

A single blinking red dot.