George Smiley (Gary Oldman), a recently retired MI6 agent, does his best to adjust to a life outside the secret service. However, when a disgraced agent reappears with information concerning a mole at the heart of the service, Smiley is drawn back into the murky field of espionage. Tasked with investigating which of his trusted former colleagues has chosen to betray him and their country, Smiley narrows his search to four suspects - all experienced, skilled and successful agents - but past histories, rivalries and friendships make it far from easy to pinpoint the man who is eating away at the heart of the British establishment. An acting masterclass from the crème de la crème of British film; Gary Oldman (Darkest Hour); Colin Firth (The King's Speech); Tom Hardy (Inception); Benedict Cumberbatch (The Imitation Game) and inspired direction from Let the Right One In's Tomas Alfredson make this gripping and tense adaptation of John le Carré's classic spy novel essential viewing.