Istanbul Passage by Joseph Kanon
Leon Bauer is, or appears to be, just an agent for American tobacco interests in Turkey. Rejected for military service, he's spent several years in Istanbul, learning the language and customs and steeping himself in the beautiful city that sits between East and West. With his German refugee wife, Anna, he has made Istanbul his home. Even after World War II ends, he has no desire to return to the United States.
Leon's other life is on the fringes of the intelligence community. He does occasional side jobs, mostly package deliveries, for a friend at the U.S. consulate. But when he gets an assignment to pick up a human package from a fishing boat one night, the job goes very wrong. Now, Leon has left the fringes of the murky world of espionage and is left stranded in its dangerous center, not knowing whom he can trust, and improvising to complete his task on his own.
Leon may be new to the ruthless world of the secret agent, but he is soon drawn into its moral ambiguities and compromises; using friends, even when it places them in danger and even as he learns how unworthy Alexei is of his help.
This is not a shoot-'em-up, action-packed thriller, but one that puts you into its time and place, and in the mind of a man trying to figure out where his loyalties lie within it, and what choice to make when all the alternatives are bad.
Note: Istanbul Passage was published by Atria Books in May 2012. A version of this review appears on the Amazon product page, under my Amazon user name.