The recipient of the message had been more cautious than the sender. Still, the sender’s early mistake had effectively nullified the recipient’s care. As a result, the MI5 technician had been able to locate the entire exchange of messages, along with a martyrdom video. The subject addressed the camera in a London accent, with his face concealed. MI5’s linguistics experts reckoned he was from North London, that he was native born, and likely of Egyptian ancestry. With the help of GCHQ, Britain’s signals intelligence service, MI5 was frantically comparing the man’s voice to known Islamic radicals. What’s more, MI5 and SO13, the Counter Terrorism Command of the Metropolitan Police, were monitoring known extremists and suspected members of ISIS. In short, the entire national security apparatus of the United Kingdom was in quiet but efficient panic mode.

By six o’clock, as the skies beyond Amanda’s windows were beginning to brighten, all efforts to identify and locate the suspected suicide bomber had proven fruitless. Prime Minister Jonathan Lancaster, in the Cabinet Room at Number 10, convened a videoconference at half past. He opened it with a question no counterterrorism professional ever wanted to hear. “Should we cordon off Westminster and order an evacuation of the surrounding districts?” One by one, his senior ministers, civil servants, intelligence chiefs, and police commissioners gave their answers. Their recommendation was unanimous. Close Westminster. Shut down all rail, bus, and commuter traffic into central London. Begin an orderly and thorough evacuation.

“And what if it’s a hoax? Or a bluff? Or what if it’s based on bad intelligence? We’ll look like Chicken Little. And the next time we say the sky is falling, no one will believe us.”

The intelligence, everyone agreed, was as good and timely as it gets. And they were rapidly running out of other options to prevent a monumental disaster.

The prime minister’s eyes narrowed. “Is that you I see, Mr. Allon?”

“It is, Prime Minister.”

“And what say you?”

“It’s not my place, sir.”

“Please don’t stand on ceremony. You and I know each other too well for that. Besides, there isn’t time.”

“In my opinion,” said Gabriel carefully, “it would be a mistake to order closures and evacuations.”

“Why?”

“Because you’ll lose your one and only chance to stop the attack.”

“Which is?”

“You know the time and place it will occur. And if you try to cordon off the center of London, you’ll incite mass panic, and the suicide bomber will simply choose a secondary target.”

“Go on,” instructed the prime minister.

“Keep the entrances to Westminster wide open. Place CBRN teams and undercover SCO19 firearms officers at strategic points around Parliament and Whitehall.”

“Let him walk straight into a trap? Is that what you’re saying?”

“Exactly, Prime Minister. He won’t be hard to miss. He’ll be overdressed for the summer weather, and the detonator will be visible in one of his hands. He’ll probably be sweating with nerves and reciting prayers. He might even be suffering from radiation sickness. And when he walks past a Geiger counter,” said Gabriel in conclusion, “he’ll light it up. Just make sure the firearms officer who goes after him has the nerve and experience to do what’s necessary.”

“Any candidates?” asked the prime minister.

“Only two,” said Gabriel.

69

Parliament Square, London

“I think this is the beginning of a beautiful friendship.”

“Or the end of one.”

“Why are you always so fatalistic?” asked Keller. “We’re not in the Sahara anymore. We’re in the middle of London.”

“Yes,” said Gabriel, looking around. “What could possibly go wrong here?”

They were seated on a bench at the western edge of Parliament Square. It was a fine summer’s morning, cool and soft, with a promise of rain later in the day. Directly behind them was the Supreme Court, the highest court in the realm. To their right were Westminster Abbey and the medieval St. Margaret’s Church. And directly before them, across the green lawn of the square, was the Palace of Westminster. The clock in the iconic bell tower read five minutes to nine o’clock. Rush-hour traffic was flowing across Westminster Bridge and up and down Whitehall, past Her Majesty’s Revenue and Customs, the Foreign and Commonwealth Office, the Ministry of Defense, and the entrance to Downing Street, official residence of the prime minister. Yes, thought Gabriel again. What could possibly go wrong?

He wore a radio earpiece in his right ear and a gun at the small of his back. The gun was a 9mm Glock 17, the standard-issue sidearm of SCO19, the tactical firearms unit of London’s Metropolitan Police. The radio was connected to the Met’s secure communications network. The head of SO15, the Counter Terrorism Command, was running the show, with assistance from Amanda Wallace of MI5. Thus far, they had identified two potential suspects approaching Westminster. One was coming across the bridge from Lambeth. The other was making his way along Victoria Street. In fact, at that very instant, he was walking past New Scotland Yard. Both men were carrying backpacks, hardly unusual in London, and both were Middle Eastern or South Asian in appearance, also not unusual. The man coming across the bridge had started his journey in the borough of Tower Hamlets in East London. The one walking past New Scotland Yard had come from the Edgware Road section of North London. He was warmly dressed and looked to be suffering from the flu.