A young Oxford academic and his attorney girlfriend holiday in Morocco. They bump into a Russian millionaire who owns a peninsula and a diamond watch. He wants a game of tennis. What else he wants propels the lovers on a tortuous journey to the City of London and its unholy alliance with Britain's intelligence establishment, to Paris and the Alps.

Academy Award-winning documentarian Errol Morris pulls back the curtain on the storied life and career of former British spy David Cornwell — better known as John le Carré, author of such classic espionage novels as The Spy Who Came in from the Cold, Tinker Tailor Soldier Spy and The Constant Gardener. Set against the turbulent backdrop of the Cold War leading into present day, the film spans six decades as le Carré delivers his final and most candid interview, punctuated with rare archival footage and dramatized vignettes. "The Pigeon Tunnel" is a deeply human and engaging exploration of le Carré's extraordinary journey and the paper-thin membrane between fact and fiction.

In the bleak days of the Cold War, espionage veteran George Smiley is forced from semi-retirement to uncover a Soviet mole within his former colleagues at the heart of MI6.