“I’m having coffee with the foreign secretary at nine. And don’t forget we’re having drinks at Downing Street tonight.”

“I won’t forget.”

Robert Halton folded his newspaper and looked at his daughter seriously.

“I want you and your friends to be careful out there. NCTC raised the threat level in Europe yesterday.”

NCTC was the National Counterterrorism Center.

“Anything specific?”

“It was vague. Heightened activity among known al-Qaeda cells. The usual crap. But that doesn’t mean we should ignore it. Take a couple Marines with you for good measure.”

“The Marines are only supposed to guard the embassy itself. If they start leaving the premises, Scotland Yard will throw a fit. And I’ll be back on the treadmill in the gym.”

“There’s no law against American Marines running in Hyde Park -at least, not yet. I suppose if Red Ken has his way there will be soon.” He tossed the newspaper onto his desk. “What’s on your calendar for today?”

“A conference on African health care issues and afternoon tea at the Houses of Parliament.”

“Still glad we came to London?”

“I wouldn’t have traded it for the world.” She stood up and headed toward the door. “Give my best to the foreign secretary.”

“Don’t forget drinks at Downing Street.”

“I won’t forget.”

Elizabeth left her father’s office and rode the elevator down to the atrium. Four other people, attired as she was in cold-weather athletic suits, were already there: Jack Hammond, the embassy’s public affairs officer; Alex Baker, an FBI special agent who served as legal affairs liaison, Paul Foreman from Consular, and Chris Petty from the State Department’s Bureau of Diplomatic Security. Petty served as London ’s Regional Security Officer, which meant he was responsible for the safety of the embassy and its staff. Two of Petty’s assistant RSOs arrived a moment later. Their matching blue tracksuits did little to conceal the fact that they were powerfully built and well armed.

“Where’s Kevin?” Elizabeth asked.

Kevin Barnett, the CIA’s deputy chief of station, rarely missed the morning run when he was in town.

“Stuck in his office,” said Chris Petty.

“Anything to do with that NCTC alert?”

Petty smiled. “How did you know about that?”

“I’m the ambassador’s daughter, Chris.”

Alex Baker looked at his watch. “Let’s get rolling. I have a nine o’clock at New Scotland Yard.”

They headed outside and slipped through a gate in the north fence reserved for embassy personnel. A moment later they were jogging west along Upper Brook Street, heading for Hyde Park.

The Ford Transit panel van was painted forest green and bore a stencil on the side that read: ADDISON amp; HODGE LTD. ROYAL PARKS CON-TRACTORS. The van did not belong to Addison amp; Hodge but was a meticulously produced forgery, just like a second one already inside Hyde Park. As the group of Americans came trotting along Upper Brook Street, the man behind the wheel watched them calmly, then pressed a button on his mobile phone and brought it to his ear. The conversation he conducted was coded and brief. When it was over he slipped the phone into the pocket of his coverall-also a forgery-and started the engine. He entered the park through a restricted access point and made his way to a stand of trees north of the Serpentine lake. A sign read AUTHORIZED VEHICLES ONLY, and warned of heavy fines for violators. The man behind the wheel climbed out and started collecting rubbish, praying softly to himself while he worked. In the name of Allah, the beneficent, the merciful…master of the day of judgment…show us the straight path…

L ater, during the inevitable Congressional inquiry, much emphasis would be placed on determining precisely when and how the intelligence services of the United States first became aware of the calamity about to befall London. The answer was 2:32 A.M. local time, when a telephone call from an individual identified only as an FIS, or “foreign intelligence source,” arrived on an emergency line in the seventh-floor executive suite of CIA Headquarters in Langley, Virginia. The foreign intelligence source, though never identified, was Gabriel, and the emergency line he dialed belonged to none other than Adrian Carter, the CIA’s deputy director of operations. In normal times, the call would have been automatically transferred to Carter’s home in nearby McLean. But these were hardly normal times, and, in spite of the appalling hour, Carter was standing in the window of his office anxiously awaiting word on the outcome of a sensitive operation under way in the mountains of Pakistan.

Aside from the grand view toward the Potomac, there was little about Carter’s lair to suggest it belonged to one of the most powerful members of Washington ’s vast intelligence establishment. Nor would one have guessed as much from Carter’s rather churchy appearance. Only a handful of people in Washington knew that Adrian Carter spoke seven languages fluently and could understand at least seven more. Or that Carter, before his ascension to the rarified atmosphere of Langley ’s seventh floor, had been one of his nation’s most faithful clandestine warriors. His fingerprints were on every major American covert operation of the last generation. He’d tinkered with the odd election, toppled the odd government, and turned a blind eye to more executions and murders than he could count. Morality had rarely entered into Carter’s calculus. Carter was Operations. Carter didn’t make policy, he simply carried it out. How else to explain that, within the span of a single year, he’d done the Lord’s work in Poland and propped up the Devil’s regime in Salvador? Or that he’d showered dollars and Stingers on the Muslim holy warriors in Afghanistan, even though he knew one day they would rain fire and death on him.

These days, longevity was Carter’s most notable achievement. The sages of Langley liked to joke that the war on terror had claimed more lives in the Operations Directorate than in the top ranks of al-Qaeda. Not Carter’s, though. He had survived the blood purges and the nights of long knives and even the horrors of reorganization. The secret to his endurance lay in the fact that he had been right far more often than he had been wrong. In the summer of 2001, he had warned that al-Qaeda was planning a major attack on American soil. In the winter of 2003, he had cautioned that some of the sources regarding Iraq ’s weapons program were suspect, only to be overruled by his director. And as war loomed in Mesopotamia, he had written a secret memorandum forecasting that Iraq would become another Afghanistan, a proving ground for the next generation of jihadists, a generation that would ultimately be more violent and unpredictable than the last. Carter laid claim to no special powers of analysis, only a clarity of thinking when it came to the intentions of his enemy. Fifteen years earlier, in a mud hut outside Peshawar, a man with a turban and a beard had told him that one day the forces of Islam would turn America to ashes. Carter had believed him.

And so it was this Carter-Carter the secret warrior, Carter the survivor, Carter the pessimist-who, in the early morning of that ill-fated Friday in December, wearily brought his telephone to his ear expecting news from a distant land. Instead he heard the voice of Gabriel, warning that there was about to be an attack in London. And Carter believed him.

Carter jotted down Gabriel’s number, then severed the connection and immediately dialed the operations desk at the National Counterterrorism Center.

“How credible is the information?” the duty officer asked.

“Credible enough for me to be calling you at two thirty-four in the morning.” Carter tried to keep his temper in check. “Get the RSO at the embassy on the phone immediately and tell him to put the entire compound and staff on lockdown until we get a better handle on the situation.”

Carter hung up before the duty officer could pose another inane question and sat there for a moment, feeling utterly helpless. To hell with the NCTC , he thought. He would take matters into his own hands. He dialed the CIA station at the London embassy and a moment later was talking directly to Kevin Barnett, the deputy COS. Barnett, when he spoke for the first time, sounded deeply shaken.

“There’s a group of embassy personnel that does a run in Hyde Park every morning.”

“You’re sure?”

“I’m usually one of them.”

“Who else goes?”

“The chief press officer, the FBI liaison, the Regional Security Officer…”

“Jesus Christ,” Carter snapped.

“It gets worse.”

“How much worse?”

“Elizabeth Halton.”

“The ambassador’s daughter?”

“I’m afraid so.”

“What time do they leave?”

“Seven-fifteen sharp.”

Carter looked at his watch. It was 7:36 in London.

“Get them back inside the embassy, Kevin. Run over to Hyde Park and do it yourself if you have to.”

The next sound Carter heard was the sound of the deputy COS in London slamming down the phone. Carter hung up, waited ten seconds, and called Gabriel back.

“I think I may have a group of diplomats running in Hyde Park at the moment,” he said. “How quickly can you get down there?”

Carter heard another click.

They had entered the park through Brook Gate, headed south along Broad Walk to Hyde Park Corner, then westward along Rotten Row, past the Rose Garden and the Dell. Elizabeth Halton moved to the front of the pack when they reached the Albert Memorial; then, with a DS agent at her side, she steadily increased the pace as they headed north up Lancaster Walk to Bayswater Road. Jack Hammond, the embassy spokesman, slipped past Elizabeth and pushed the pace hard to Victoria Gate, then down the West Carriage Drive to the shore of the Serpentine. As they approached the boathouses, a mobile phone began to ring. It belonged to Chris Petty, the RSO.

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.