The Spy Who Came in from the Cold by John le Carré
The West Berlin office of the British Secret Intelligence Service (known in the Le Carre novels as the Circus), under the command of Station Head Alec Leamas, has been performing poorly. At the commencement of the novel, Karl Riemeck – his last and best double agent, a high-ranking East German political officer – is shot dead at the last moment whilst defecting to West Berlin. Without any agents left, the disgraced Leamas is recalled to the Circus in London by Control, chief of the Circus. There, Control asks Leamas to stay "in the cold" for one last mission: to turn (defect) and provide false information to the East German Communists that would implicate Mundt as a British double agent — what his second-in-command, Fiedler, already suspects — to result in Mundt being executed by his own people. Control tells Leamas that Fiedler, due to his paranoia about Mundt, would be the best man to depose Mundt. George Smiley and his former assistant Peter Guillam brief Leamas for his crucial mission. Control tells Leamas that Smiley had not returned to the Circus after the events of Call for the Dead because of moral qualms about unethical Circus operations.