At the height of the Cold War, a precarious operation goes deadly wrong, and the head of British Intelligence wonders if a double agent is leaking vital secrets. Brought out of retirement to expose the potential mole, master spy George Smiley is the only one who can be trusted to expose one of their own. Or can he? As the emotional and physical tolls mount on the high-ranking suspects, Smiley will be forced into the ultimate international spy game...