Istanbul Passage by Joseph Kanon

A neutral capital straddling Europe and Asia, Istanbul survived WW2 as a magnet for refugees and spies, trafficking in secrets and lies rather than soldiers. Expatriate American businessman Leon Bauer was drawn into this shadow world, doing undercover odd jobs and courier runs in support of the Allied war effort. Now as the espionage community begins to pack up and an apprehensive city prepares for the grim realities of postwar life, Leon is given one last routine assignment. But when the job goes fatally wrong – an exchange of gunfire, a body left in the street, and a potential war criminal in his hands – Leon is plunged into a nightmarish tangle of intrigue, shifting loyalties and moral uncertainty.

Rich with atmosphere and period detail, Istanbul Passageis the story of a man swept up in the dawn of the Cold War, of an unexpected love affair, and of a city as deceptive as the calm surface waters of the Bosphorus that divides it.