THERE ARE TELLTALE INDICATORS COMMON to suicide bombers. Lips can move involuntarily as final prayers are recited. Eyes can have a glassy thousand-yard stare. And the face can sometimes appear unnaturally pale, evidence that an unkempt beard has been hastily removed in preparation for a mission. The dead man exhibited none of these traits. His lips were pursed. His eyes were clear and focused. And his face was evenly colored. He had been shaving regularly for a long time.

What set him apart was the thin tributary of sweat leaking from his left sideburn. Why was he perspiring on a crisp autumn afternoon? If he was warm, why were his hands buried in the pockets of his woolen overcoat? And why was the overcoat—a size too large, in Gabriel’s opinion—still tightly buttoned? And then there was his walk. Even a physically fit man in his late twenties will have difficulty feigning a normal gait when saddled with fifty pounds of high explosives, nails, and ball bearings. As the dead man walked past Gabriel in Wellington Street, he appeared unusually erect, as if he were trying to compensate for the added weight around his abdomen and kidneys.