Berlin Game (Bernard Samson, Book 1) by Len Deighton

When a valuable agent behind the Iron Curtain signals he wants out, it's up to Bernard Samson, once active in the field but now anchored to a London desk, to undertake the crucial rescue. But soon, Samson is confronted with evidence that there is a traitor among his colleagues. And to find out who it is, he must sift through layers of lies and follow a web of treachery from London to Berlin until hero and traitor collide. "Each scene in this story is so adroitly realized that it creates its own suspense." NEWSWEEK From the Paperback edition.