They looked like ordinary rolling suitcases. They were not. The sides and wheels had been reinforced to accommodate the weight of the explosives, and the buttons on the collapsible handles had been wired to the detonators. The bags were now in the possession of four men who, at that moment, were approaching four separate targets: the Underground stations at Piccadilly Circus, Leicester Square, Charing Cross, and Marble Arch. The men knew nothing of each other but had much in common. All four were Egyptian. All four were takfiri Muslims who embraced death as much as the infidels loved life. And all four were wearing Seiko digital watches that would sound an alarm at precisely 7:40 A.M.

It took two minutes for Gabriel to dress and get the Beretta and another minute to make his way downstairs to the street. The traffic signal along the Bayswater Road was blinking red when he arrived. He ignored it and sprinted through the oncoming traffic into the park. Just then he heard the rumble of an explosion deep underground and felt the earth shift suddenly beneath his feet. He stopped for a moment, uncertain of what he had just heard and felt, then turned and raced toward the center of the park.

Chris Petty slowed to a stop and pulled the phone out of the clip attached to the waist of his sweatpants.

“You guys go ahead,” he called out. “Take the usual route. I’ll catch up if I can.”

The rest of the group turned away from the shore of the Serpentine and headed into the stand of trees north of the lake. Petty looked at the caller ID screen. It was his office inside the embassy. He opened the phone and brought it quickly to his ear.

“Petty.”

Static…

“This is Chris Petty. Can you hear me?”

Silence…

“Shit.”

He killed the connection and set off after the others. Twenty seconds later the phone rang again. This time, when he raised it to his ear, the connection was perfect.

The man in the Addison & Hodge uniform collecting rubbish along the pathway looked up as the group of runners turned onto the footpath leading from the Old Police House to the Reformers’ Tree. The second false Addison & Hodge van was parked on the opposite side of the path, and another uniformed man was scratching at the earth with a rake. They had been preparing for this moment for over a year. Thirty seconds, the operational planner had said. If it lasts more than thirty seconds, you’ll never make it out of the park alive. The man reached into the plastic rubbish bag he was holding in his hand and felt something metallic and cold: a Heckler & Koch MP7 machine pistol, loaded with forty armor-piercing rounds. He blindly thumbed the fire-selector switch to the proper setting and counted slowly to ten.