By ten o’clock they were all famished. Unwilling to suspend work, they decided on takeaway. Gabriel voted for kebabs, Sophie for Indonesian, and Lavon for Thai. After ten minutes of spirited debate, they resorted to drawing a name from one of Rosner’s old felt hats. Sophie did the honors. “Thai,” she said, smiling at Lavon. “Shall we draw again to see who has to go pick it up?”

“I’ll go,” said Gabriel. “There’s someone I need to have a word with.”

A gentle snow was falling when Gabriel stepped outside five minutes later. He stood for a moment atop Rosner’s iron steps, buttoning his overcoat against the cold, while scanning the street for signs of surveillance. It was deserted except for a single bundled soul, perched on a public bench on the opposite bank of the canal. He wore a threadbare woolen overcoat and a black-and-white checkered kaffiyeh for a scarf. His gray beard was unkempt and atop his head was the white kufi skullcap of a devout Muslim. Gabriel descended the steps and walked to the drawbridge at the end of the street. As he turned into the Staalstraat, he could hear footfalls on the cobblestones behind him. He swiveled his head deliberately and took a long, highly unprofessional look over his shoulder. The Muslim man who had been seated on the bench was now thirty yards behind and walking in the same direction. Two minutes later, as Gabriel passed Rosner’s memorial outside Café de Doelen, he looked over his shoulder a second time and saw that the man with the kufi and the kaffiyeh had cut the distance between them in half. He thought of the words Lavon had spoken to him earlier that afternoon at the Hotel Europa. Just try not to kill anyone while we’re in Amsterdam, Lavon had said. Gabriel had no intention of killing the man. He just wanted answers to two simple questions. Why had a devout Muslim spent the better part of the evening sitting outside Solomon Rosner’s house? And why was he now following Gabriel through the dark streets of Amsterdam?

The restaurant where Sophie Vanderhaus had placed the takeaway order was in the Leidsestraat, not far from the Koningsplein. Gabriel, after crossing the Amstel, should have gone to the right. He went left instead, into a narrow pedestrian lane lined with sex shops, American fast-food restaurants, and tiny Middle Eastern cafés. It was crowded in spite of the hour; even so, Gabriel had no trouble keeping track of his pursuer in the garish neon light.

The street emptied into the Rembrandtplein, but twenty yards before the busy square Gabriel turned into a darkened shoulder-width alley that led back to the river. The man with the kaffiyeh and the kufi paused at the mouth of the alley, as though reluctant to enter, then followed after him.