The year is 1945, the place Istanbul. Leon Bauer is marking time in the city. He works for an American tobacco company and would have gone home before now, but his wife is confined to a clinic. She has been in a coma-like state for many years as a result of trying to save people on a boat that sank. Leon is at odds in his life, drifting as he waits to see if Anna will make it back to health, bored and ready for something more exciting.

That chance comes when a friend of his, Tommy, who works at the American consulate, asks Leon to get involved on the periphery of some clandestine activities. Leon is Tommy's help in getting people across borders at times, an exciting job that enlivens his boring existence. Everything changes one night when Tommy is killed as he and Leon bring in another exile. This man is someone who everyone is desperate to get. The Americans want him for his knowledge of the Germans, as do the Russians. The Turkish embassy wants him to sell him to the highest bidder.

Leon manages to get Alexei into hiding and then, as he tries to plan an escape, finds out why Alexei is so important to so many. He was a Nazi actively involved in the Jewish massacres; now there are many who are ready to get revenge. Leon wonders what the ethical way to choose is when the only options are bad choices. Should he try to get Alexei out of Istanbul, knowing that he is saving an evil man? Should he do nothing and allow Alexei to be captured, knowing that he has basically agreed to Alexei's murder?

Adding to Leon's confusion is a new relationship. Kay is the wife of another embassy employee, a man Leon has worked with over the years and who is trying to recruit him to fill Tommy's position. When Kay comes to town by herself, she and Leon fall into a relationship full of sexual tension and the knowledge of betrayal of bonds.

Joseph Kanon's fast-paced thriller is heavy with the mystique of Istanbul, the crosscurrents of conflicting loyalties, and actions that have far-reaching consequences. Nothing is as it seems on the surface; there are hidden motives that remain hidden until the last minute. The plot twists and turns, showing all sides of Leon's actions and the compulsion that moves him forward to a startling climax. Istanbul Passage is recommended for lovers of historical fiction and the spy genre.