This is the first book in the Karla trilogy by John le Carre. It was recently adapted into a movie starring Gary Oldman as the titular character George Smiley, and also involves the acting chops of Colin Firth and Mark Strong. The movie was nominated for 3 Academy Awards including Best Actor and Best Adapted Screenplay.
THE STORY: Tinker, Tailor, Soldier, Spy is a 1974 British spy novel featuring George Smiley, a middle-aged, taciturn, perspicacious intelligence expert who has been forced to retire. He is recalled to hunt down a Soviet mole in the “Circus”, the highest echelon of the Secret Intelligence Service. The story begins in media res with the repatriation of a captured British spy. The background is supplied during the book through a series of flashbacks. (Source: wikipedia)
The next 2 books in the series are: The Honourable Schoolboy and Smiley’s People.