There was other evidence as well, such as an alarming spike in coded signal traffic emanating from the roof of the Russian Embassy in Kensington Palace Gardens; and a second meeting in the Epping Forest between Charles Bennett and his SVR controller, Yevgeny Teplov; and the arrival in London, in mid-March, of one Konstantin Dragunov, personal friend and business associate of both the present ruler of Russia and the future king of Saudi Arabia. Taken in isolation, the developments were proof of nothing. But when viewed through the prism of the Anglo-Israeli team at Hatch End, they appeared to be the first stirrings of a great Russian undertaking.

It was Gabriel who had once again prodded the sleeping bear, but he monitored the Russian response not from Hatch End but from his desk at King Saul Boulevard, based on his firmly held operational conviction that a watched pot never boils. In late March he paid another clandestine visit to Khalid’s superyacht in the Gulf of Aqaba, if only to hear the latest gossip from Riyadh. Unbeknownst to the outside world, Khalid’s father had taken a turn for the worse—another stroke, perhaps a heart attack. He was attached to several machines at the Saudi National Guard Hospital. The vultures were circling, dividing up the spoils, fighting over the scraps. Khalid had requested permission to return to Riyadh to be at his father’s side. Abdullah had refused.

“If you have a card up your sleeve,” said Khalid, “I suggest you play it now. Otherwise, Saudi Arabia will soon be controlled by Comrade Abdullah and his puppet master in the Kremlin.”

A sudden storm grounded Tranquillity’s helicopter and forced Gabriel to spend that night at sea in one of the ship’s luxurious guest suites. When he returned to King Saul Boulevard the next morning he found a report waiting on his desk. It was the analysis of the stolen Iranian nuclear archives. The documents proved conclusively that Iran had been working on a nuclear weapon when it was telling the global community the precise opposite. But there was no firm evidence they were violating the terms of the nuclear accord they had negotiated with the previous American administration.

Gabriel briefed the prime minister that afternoon in his office in Jerusalem. And a week later he flew to Washington to bring the Americans into the picture. Much to his surprise, the meeting took place in the White House Situation Room, with the president in attendance. He had made no secret of his intention to withdraw the United States from the Iran nuclear deal and was disappointed that Gabriel had not brought him incontrovertible proof—“a smoking mullah”—that the Iranians were secretly building a bomb.

Later that day Gabriel traveled to Langley, where he gave a more detailed briefing to the officers of the Persia House, the CIA’s Iran operations unit. Afterward, he dined alone with Morris Payne in a wood-paneled room on the seventh floor. Spring had finally arrived in Northern Virginia after an inhospitable winter, and the trees along the Potomac were in new leaf. Over wilted greens and cartilaginous beef, they swapped secrets and naughty rumors, including some about the men they served. Like many of his predecessors at the Agency, Payne had no background in intelligence. Before coming to Langley, he had been a soldier, a businessman, and a deeply conservative member of Congress from one of the Dakotas. He was big and bluff and blunt, with a face like an Easter Island statue. Gabriel found him a refreshing change from the previous CIA director, who had routinely referred to Jerusalem as al-Quds.

“What do you think of Abdullah?” Payne asked abruptly over coffee.

“Not much.”

“Fucking British.”

“What have they done now?”

“Invited him to London before we could get him to Washington.”

Gabriel shrugged indifferently. “The House of Saud can’t survive without you. Abdullah will promise to buy a few British toys and then he’ll come running.”

“We’re not so sure about that.”

“Meaning?”

“We hear MI6 might have their hooks in him.”

Gabriel suppressed a smile. “Abdullah? A British asset? Come on, Morris.”

Payne nodded gravely. “We were wondering whether you might be interested in facilitating a change in the Saudi line of succession.”

“What kind of change?”

“The kind that eventually places KBM’s ass on the throne.”

“Khalid is damaged goods.”

“Khalid is the best we can hope for, and you know it. He loves us, and for some reason he’s reasonably fond of you.”

“What do we do about Abdullah?”

“He would have to be moved aside.”

“Moved aside?”

Payne stared at Gabriel blankly.

“Morris, really.”

After dinner Gabriel was driven in a CIA motorcade to the Madison Hotel in downtown Washington. Exhausted, he fell into a dreamless sleep but was awakened at 3:19 a.m. by an urgent message on his BlackBerry. At dawn he went to the Israeli Embassy and remained there until early afternoon, when he left for Dulles Airport. He had told his American hosts he was planning to return to Tel Aviv. Instead, at half past five, he boarded a British Airways flight to London.

Brexit had produced at least one positive impact on the British economy. Owing to a double-digit drop in the value of the pound, more than ten million foreign tourists were pouring into the United Kingdom each month. MI5 routinely screened the new arrivals for unwanted elements such as terrorists, criminals, and known Russian intelligence operatives. At Gabriel’s suggestion, the Anglo-Israeli team at Hatch End were duplicating MI5’s efforts. As a result, they knew that British Airways Flight 216 from Dulles landed at Heathrow the next morning at 6:29 and that Gabriel cleared passport control at 7:12. They even found several minutes of video of his passage through the endless non-EU immigration queue. It was playing on a loop on one of the large-screen video monitors when he entered the makeshift op center.

Sarah Bancroft, in jeans and a fleece pullover, directed his attention to the adjacent video screen. On it was a still image of a lean, well-built man in a peacoat walking across a car park at night. A bag hung from his right shoulder. An American-style baseball cap obscured most of his face.

“Recognize him?” she asked.

“No.”

Mikhail Abramov aimed a remote at the screen and pressed play. “How about now?”

The man approached a Toyota hatchback, tossed the bag into the backseat, and dropped behind the wheel. The lights burst on automatically when the engine started, a small mistake in tradecraft. The man quickly switched them off and reversed out of the space. A few seconds later the car disappeared from the camera’s view.

Mikhail hit pause. “Nothing?”

Gabriel shook his head.

“Watch it again. But this time pay careful attention to the way he walks. You’ve seen it before.”

Mikhail played the video a second time. Gabriel focused only on the man’s athletic gait. Mikhail was right, he had seen it before. The man had walked past the front of Gabriel’s car in Geneva, a few minutes after leaving his briefcase behind at Café Remor. Mikhail had been walking a few paces behind him.

“I wish I could take credit for spotting him,” he said, “but it was Sarah.”

“Where was the video taken?”

“The car park at the Holyhead ferry terminal.”

“When?”