At one that afternoon the negotiators broke for lunch. The morning session had been particularly unproductive because both sides were still in a panic over Gabriel’s missing radioactive material. Reza Nazari slipped away from his delegation long enough to telephone Yaakov Rossman at the InterContinental. Yaakov then rang Keller at the safe flat and repeated the message.

“Radio silence from Moscow. No word from Alexei.”

By then, it was approaching two o’clock. The skies were low and leaden; a few flakes of snow were blowing sideways beyond the windows of the safe flat. Except for Nazari’s interrogation, Gabriel had been a prisoner of its rooms, hidden from view, shielded from the memories lurking just outside his door. It was Keller who suggested a walk. He helped Gabriel into his coat, wrapped a scarf around his neck, and pulled a hat low over his brow. Then he gave him a gun, a .45-caliber Glock, a man stopper, a weapon of mass destruction.

“What am I supposed to do with this?”

“Shoot any Russian who asks you for directions.”

“What if I run into an Iranian?”

“Go,” said Keller.

By the time Gabriel stepped from the building, the snow was dropping from the sky straight and steady, and the pavements looked like sugar-dusted Viennese cakes. He walked blindly for a few moments, not bothering to check whether he was being followed. Vienna had long ago made a mockery of his tradecraft. He loved its beauty, he hated its history. He was envious of it. He pitied it.

The safe flat was located in Vienna’s Second District. Before the war it had been so heavily Jewish that the Viennese derisively referred to it as the Mazzesinsel, or the Matzo Island. Gabriel crossed the Ringstrasse, leaving the Second District for the First, and paused outside Café Central, where he had once encountered a man named Erich Radek, a former SS officer who had been ordered by Adolf Eichmann to conceal evidence of the Holocaust. Then he walked the short distance to Radek’s stately old mansion, from which a team of Office agents had plucked the war criminal and started him on the first leg of a journey that would end in an Israeli jail cell. Gabriel stood alone at the gate as the snow whitened his shoulders. The exterior of the house was worn and cracked, and the curtains hanging in the unwashed windows appeared threadbare. It seemed no one wanted to reside in the home of the murderer. Perhaps, thought Gabriel, there was hope for them after all.