The storm had finally broken over London.

Sheets of rain hammered the Thames Barrier control station, turning the river into a churning mass of black water. Inside the dim operations room, the glow of decrypted files flickered across Mercer’s pale face. Jake and Emma stood behind him, silent, tense, waiting for the truth to reveal itself.
Mercer wiped sweat from his brow. “I have reconstructed forty per cent of the asset logs. Enough to prove Harris was running a shadow network.”
Emma leaned closer. “And the Sleeper Grid?”
Mercer hesitated. “Still encrypted. Whatever this Grid is… It is buried deep.”
Jake paced behind them, jaw tight. “Harris did not build it alone. Someone else is pulling the strings.”
Emma nodded. “The figure in the epilogue feeds. The one who activated the Grid.”
Mercer swallowed. “Whoever they are… they outrank Harris.”
Jake stopped pacing. “Then we find them.”
Before Mercer could respond, the lights flickered.
Once.
Twice.
Then the entire station went dark.
Emma’s hand went to her weapon. “Jake—”
“I know.”
A low hum filled the room as emergency power kicked in. Red lights bathed the walls, turning the control station into a pulsing heartbeat of danger.
Mercer’s laptop rebooted itself.
Lines of code flashed across the screen.
Then a message appeared.
UNIT 47 — ACTIVE
TARGET: MERCER
Emma’s breath caught. “They found us.”
Jake grabbed Mercer. “Move!”
The first explosion hit the side of the building.
Concrete dust rained from the ceiling. The windows shook violently. The river outside surged against the barrier gates.
Emma shouted over the noise. “They’re breaching the west wall!”
Jake dragged Mercer toward the stairwell. “Go! Go!”
Another explosion. Closer.
The metal walkway buckled under the shockwave. Sirens blared. The entire building groaned as if it were being torn apart.
Emma fired a burst toward the shattered window as a black-clad figure rappelled down the exterior wall. “Sleeper unit! They are here!”
Jake shoved Mercer through the stairwell door. “Downstairs! Now!”
They sprinted down the narrow metal steps as the building shook again. Dust filled the air. Pipes burst overhead, spraying steam into the corridor.
Mercer stumbled. Jake caught him. “Keep moving!”
Emma covered their retreat, firing controlled shots at the shadows closing in behind them.
They reached the lower level — a maintenance corridor running beneath the barrier.
Jake slammed the door shut behind them. “Mercer, where’s the exit?”
Mercer pointed down the corridor. “Floodgate access tunnel. Leads to the riverbank.”
Emma frowned. “And if the tide’s high?”
Mercer looked sick. “We swim.”
Jake did not hesitate. “Then we swim.”
They ran.
The corridor lights flickered as the Sleeper unit breached the upper floors. The sound of boots echoed above them — fast, coordinated, relentless.
Emma glanced back. “They’re tracking us.”
Jake nodded. “They’re not here to capture Mercer.”
Mercer swallowed. “They’re here to erase me.”
Jake grabbed his arm. “Not today.”
They reached the floodgate access hatch. Jake spun the wheel, muscles straining. The hatch groaned open, revealing a narrow tunnel leading to the river.
Cold air blasted in.
Emma stepped through first. “Clear!”
Jake pushed Mercer through—
A gunshot rang out.
Mercer cried out, collapsing against the tunnel wall.
Emma screamed, “Mercer!”
Jake spun, weapon raised.
A Sleeper operative stood at the far end of the corridor, rifle aimed, mask expressionless.
Jake fired.
The operative dropped.
But more shadows appeared behind him.
Jake grabbed Mercer, hauling him into the tunnel. “Emma — seal it!”
Emma slammed the hatch shut and spun the wheel. Bullets hammered the metal from the other side.
Jake pressed Mercer against the tunnel wall. Blood seeped through his fingers.
Emma knelt beside him. “Mercer, stay with me.”
Mercer gasped, “They… they activated the Grid. Hundreds of them. Thousands.”
Jake leaned close. “Who leads them? Who is behind Harris?”
Mercer’s eyes fluttered. “A name… I saw a name in the logs…”
Emma shook him gently. “Mercer, focus.”
Mercer whispered, voice barely audible.
“Codename: Helix.”
Jake froze.
Emma whispered, “Who the hell is Helix?”
Mercer’s eyes closed.
“They’re not MI5,” he breathed. “They’re above it.”
Jake felt the chill run through him.
Above MI5.
Above Harris.
Above everything.
Emma looked at Jake. “What do we do?”
Jake stared down the dark tunnel, jaw set, eyes burning with fury.
“We hunt Helix.”
He lifted Mercer onto his shoulder.
“And we tear the Sleeper Grid apart.”
Behind them, the hatch buckled under the attackers’ force.
Jake turned toward the river.
“Operation Retribution starts now.”