“The cold air is good for you,” Carter said. “It lends clarity to one’s thoughts. It steels one’s resolve for the travails that lay ahead.”

They slipped from the OHB through a side exit and set out along a paved jogging trail through the trees overlooking the river. Carter was bundled in a thick toggle coat and wool hat. Gabriel had only the leather jacket he’d taken with him the previous morning to Cyprus and within a few moments he was numb with cold.

“All right,” Carter said. “No one’s listening now. How did you know they were going to strike in London?”

“No one’s listening?” Gabriel looked around at the trees. “This place is littered with cameras, motion sensors, and hidden microphones.”

“That’s true,” said Carter. “But answer the question anyway.”

Gabriel told him about the tip he had received from Ibrahim Fawaz, the photographs he discovered during his hasty search of Samir al-Masri’s apartment, and the lines on the legal pad he had correctly identified as a sketch of Hyde Park.

“Amazing,” said Carter with genuine admiration in his voice. “And what was the great Gabriel Allon doing in Amsterdam?”

“I’m afraid you don’t get to know that part of the story.”

Carter, a consummate professional, moved on without objection. “Ibrahim Fawaz sounds like exactly the sort of Muslim we’ve been looking for—a man who’s willing to expose the extremists and terrorists residing within his community and his mosque.”

“That’s what I thought, too. Unfortunately, there’s a catch. Inside that suitcase I brought with me is a substantial portion of the SSI’s dossier on the Sword of Allah. Guess whose file I found in there?”

“Your source is Sword of Allah?”

Gabriel nodded. “Before leaving Egypt, Dr. Ibrahim Fawaz served as a professor of economics at the University of Minya. According to his file, he was one of the group’s earliest organizers. He was arrested after Sadat’s assassination. The file is a bit vague on the reasons why, along with the duration of his detainment.”

“They usually are,” Carter said. “Why did he leave Egypt and come to Europe? And why did he tell you there was a plot being organized from within the al-Hijrah Mosque in west Amsterdam?”

“Obviously someone needs to put those very questions to him—and sooner rather than later. He lied to me or didn’t tell me the whole story. Either way, he was being deceptive. He’s hiding something, Adrian.”

They came to the intersection of two pathways. Carter guided Gabriel to the left, and together they set out through a stand of leafless trees. Carter dug a pipe and a pouch of tobacco from the pocket of his overcoat and slowly loaded the bowl. “They don’t let us smoke in the building anymore,” he said, pausing to ignite the tobacco with an elegant silver lighter.