“You wouldn’t.”

The line went dead. Gabriel placed the receiver back in the cradle. We’re having dinner together tonight at Kaplan Street… He supposed he knew what the topic of conversation would be. Apparently Amos didn’t have long to live. He looked at the television screen. Three telegenic young people were engaged in a deeply serious discussion about the sexual antics of Britain ’s most famous footballer. Gabriel groped for the remote control and instead found Samir’s legal pad. Then he remembered waking in the middle of the night and gazing at the image-not the pine trees and the sand dunes but the pattern of crisscrossing lines.

He looked at it again now. Gabriel had been blessed with near-perfect visual recall, a skill enhanced by his study of art history and his work as a restorer. He had hundreds of thousands of paintings stored in the file rooms of his memory and could authenticate a work simply by examining a few brushstrokes. He was convinced the lines were not random but part of a pattern-and he was certain he had seen the pattern somewhere before.

He went into the kitchen and made coffee, then carried his cup over to the window. It was beginning to get light, and the London morning rush was in full force. A woman who looked too much like his former wife was standing on the corner, waiting for the light to change. When it did, she crossed the Bayswater Road and disappeared into Hyde Park.

Hyde Park …

He looked at the notepad, then looked out the window again.

Was it possible?

He walked over to the desk and opened the top drawer. Inside was a London A-Z street atlas. He took it out and opened it to map number 82. It showed the northeast corner of Hyde Park and the surrounding streets of Mayfair, Marylebone, Bayswater, and St. John’s Wood. The footpaths of the park were represented with dotted lines. Gabriel compared the pattern to Samir’s markings on the legal pad.

They matched perfectly.

Hyde Park …

But why would a terrorist want to attack a park?

He thought of the pictures he’d found in Samir’s flat: Samir in Trafalgar Square. Samir with a member of the Queen’s Life Guard outside Buckingham Palace. Samir riding the Millennium Wheel. Samir outside the Houses of Parliament. Samir with four friends posing in front of the American embassy in Grosvenor Square…

He looked at the map in the London A-Z again. Grosvenor Square was two blocks east of the park in Mayfair. He picked up the telephone and dialed.

“Graham Seymour.”

“I want you to warn the Americans about the Amsterdam cell.”

“What Amsterdam cell?”

“Come on, Graham-there isn’t time.”

“Immigration spent the night looking for them. So far they’ve come up with no evidence to suggest any of the men whose names you gave me are even in the country.”

“That doesn’t mean they’re not here.”

“Why do you think they’re going to go after the Americans?”

Gabriel told him.

“You want me to sound the alarm at Grosvenor Square because of some lines on a legal pad?”

“Yes.”

“I’m not going to do that. There’s not enough evidence to support making a call like that. Besides, have you been to Grosvenor Square lately? It’s an American fortress now. A terrorist can’t get close to that building.”

“Call them, Graham. If you don’t, I will.”

“Listen to me, Allon, and listen very carefully. If you make a mess of my town, so help me God, I’ll-”

Gabriel severed the connection and dialed another number.

T he streets at the northern end of posh Mayfair have a distinctly American flavor. Tucked amid the stately Georgian buildings one can find the headquarters of the American Chamber of Commerce, the American Club, the American Church, the American Society, and the Society of American Women. Along the northern side of Grosvenor Square is the U.S. Navy building, and on the western side stands the American embassy. Nine stories in height and adorned by a monstrous gilded eagle, it is one of the largest American diplomatic missions in the world and the only one to reside on land not owned by the federal government. The Duke of Westminster, who owns most of Mayfair, leases the property to the American government for the very reasonable sum of a single peppercorn a year. There is little danger the Americans will be evicted from their patch of Mayfair any time soon, since the lease on the property does not expire until Christmas Day in the year 2953.

Fifty-eight men and a single woman have served as the American ambassador to the Court of St. James’s-including five who would become president-but only one has ever come from the ranks of the career Foreign Service. The rest have been political appointees and diplomatic debutants, known more for their money and connections than their foreign policy expertise. Their names read like an honor roll of American high society and wealth: Mellon, Kennedy, Harriman, Aldrich, Bruce, Whitney, and Annenberg.

The current American ambassador to the Court of St. James’s, Robert Carlyle Halton, was not born to wealth, and few Americans knew his name, though he was by far the richest man to ever occupy the post and his political connections were second to none. The president and CEO of the Denver-based Red Mountain Energy, Halton’s personal fortune exceeded five billion dollars at last estimate. He also happened to be a lifelong friend of the president of the United States and his largest political donor. The Washington Post , in a rather unflattering profile of Halton published shortly after his nomination, declared that he “had pulled off the extraordinary political feat of putting his best friend in the White House.” When asked about the accuracy of the report during his confirmation hearings, Halton said he only wished he had been able to give the president more money, a remark that had cost him several Democratic votes.

Despite the fact Robert Halton was no longer responsible for a global energy empire, he remained an early riser and kept a rigorous daily schedule that was far more punishing than those of his predecessors. As usual that morning, he had left Winfield House, his official residence in Regent’s Park, at the thoroughly undiplomatic hour of 6:45, and by seven he was leafing through the London papers at his desk overlooking Grosvenor Square. The pages were filled with dire news from Iraq. Halton was convinced the British, who had already made drastic cuts to their troop levels in Iraq, would soon be looking for the exits entirely, an assessment he had given directly to the president during their last meeting at Halton’s sprawling Owl Creek estate in Aspen. Halton hadn’t minced words during the meeting. He rarely did.

At 7:10, a tall young woman dressed in a cold-weather tracksuit and fleece headband appeared in his doorway. She had long dark hair, pale green eyes set in an attractive face, and a trim athletic figure. Without waiting for permission to enter, she crossed the room and sat on the arm of Halton’s chair. It was a gesture of obvious intimacy, one that might have raised eyebrows among the embassy staff were it not for the fact that the attractive woman’s name was Elizabeth Halton. She kissed the ambassador’s cheek and smoothed his head of thick gray hair.

“Good morning, Daddy,” she said. “Anything interesting in the papers?”

Robert Halton held up the Times . “The mayor of London is angry at me again.”

“What’s eating Red Ken now?”

Halton’s relations with London’s infamously left-wing mayor were frosty at best-hardly surprising, given the fact that the mayor had expressed compassion for the suicide bombers of Hamas and had once publicly embraced a Muslim Brotherhood leader who had called for the murder of Jews and other infidels.

“He says our security is causing major disruptions to the flow of traffic throughout Mayfair,” Robert Halton said. “He wants us to pay a congestion tax. He’s suggesting I pay for it out of my personal funds. He’s quite sure I won’t miss the money.”

“You won’t.”

“That’s not the point.”

“Shall I have a word with him?”

“I wouldn’t inflict that on my worst enemy.”

“I can be a charmer.”

“He doesn’t deserve you, darling.”

Robert Halton smiled and stroked his daughter’s cheek. The two had been nearly inseparable since the death of Halton’s wife five years earlier in a private-plane crash in northern Alaska -so inseparable, in fact, that Halton had refused to accept the president’s offer to become his envoy to London until first making certain Elizabeth would accompany him. While most young women would have leaped at the chance to live in London as the daughter of the American ambassador, Elizabeth had been reluctant to leave Colorado. She was one of the most highly regarded emergency-room surgeons in Denver and was discussing marriage with a successful real estate developer. She had wavered for several weeks, until one evening, while on duty at Denver ’s Rose Medical Center, she had received a call from the White House on her mobile phone. “I need your father in London,” the president had said. “What do I have to say to you to make that happen?”

Few people were better positioned to turn down a request from the commander in chief than Elizabeth Halton. She had known the president her entire life. She had skied with him in Aspen and hunted deer with him in Montana. She had been toasted by him on the day she graduated from medical school and comforted by him on the day her mother was buried. But she had not turned him down, of course, and upon her arrival in London had thrown herself into the assignment with the same determination and skill with which she approached every other challenge in life. She ruled Winfield House with an iron hand and was nearly always on her father’s arm at official events and important social affairs. She did volunteer work in London hospitals-especially those that served the poor immigrant communities-and was a skillful public advocate for American policy in Iraq and the broader war on terror. She was as popular with the London press as her father was loathed, despite the fact that the Guardian had published a little-known fact that Elizabeth, for reasons of security, had tried to keep secret. The president of the United States was her godfather.

“Why don’t you skip the newspapers this morning and come out for a run with us?” She patted his midsection. “You’re starting to put on weight again.”