A figure like him, Janson knew, became invisible by virtue of standing out. If the spirit gum on his cheeks itched, and the woolen cloak was uncomfortably hot, it was easy to produce the low-grade anxiety that his role called for. He let the breeze cool him, dry his sweat. There wasn’t any reason to doubt that he was who his passport said he was; from time to time, he took out a small, plastic-encased photograph of the late Rabbi Schneerson, considered by many Hasids to be the messiah, or mosiach, and regarded it lovingly. Such details mattered when one was in character.

He turned around slowly, hearing the footfalls of someone approaching him. His stomach dropped as he took in the man’s round-brimmed hat and severe black garb. It was a Hasid—a real one. A fellow Hasid, he told himself urgently. You are who you pretend to be—it was an honored koan of spycraft. Another, though, was not to be an idiot about it.

The other man, shorter than Janson, and perhaps in his early forties, smiled at him. “Voos hurst zich?” he said, bowing his head a little. His hair was reddish, his eyes a watery blue beneath plastic National Health spectacles. A small leather portfolio was tucked beneath an arm.

Janson bobbed his head, clutching his briefcase, and gave him a cautiously friendly smile, a smile constrained by the imperfect plasticity of the facial adhesive he had employed. How to respond? There were people who had a gift for acquiring new languages, sometimes with uncanny fluency; Alan Demarest was one. Janson, though he had decent German and French from his days as a student, and a certain amount of Czech, gleaned from his Czech-speaking mother, was not among them. Now, he racked his brain, trying to dredge up some scrap of Yiddish. It was an eventuality he should have foreseen. Rather than venture a simpering “shalom,” he would be safest discouraging any conversation. He had a fleeting fantasy of hurling the inconvenient interloper over the side. After a moment, he gestured toward his throat, and shook his head. “Laryngitis,” he whispered, in some approximation of an East End accent.

“Ir filt zich besser?” the man said with a kindly look. He was a lonely soul, undeterred in his attempt to bond with someone he took to be spiritual kin.

Janson coughed explosively. “Sorry,” he whispered. “Very contagious.”

The other man took a few steps back, alarmed. He bowed again, clasping his hands together. “Sholem aleichem. Peace and blessings be upon you,” he said, and shakily raised a hand in farewell, retreating politely but swiftly.

Once more, Janson surrendered himself to the cooling head wind. We know more than we know, Demarest used to admonish. Janson believed that it was true in this case—that he could make progress if only he could properly assemble the data points he already had.