A leak is traced to a small sub-section of the secret service, sparking off the inevitable security checks, tensions and suspicions. The sort of atmosphere, perhaps, where mistakes could be made? For Maurice Castle, it is the end of the line anyway, and time for him to retire to live peacefully with his wife and child. But no-one escapes so easily from the lonely, isolated, neurotic world of the SIS.

A young boy, Victor, is collected from school by a stranger in a bowler hat - the stranger says he has won Victor in a game of backgammon with Victor's father. The stranger, known as the Captain, takes Victor to live with the sweet but withdrawn Lisa, where he serves as her conduit to the outside world. From mysterious beginnings, Graham Greene's final novel becomes a twisting thriller of smuggling, jewel theft and international espionage which culminates in a dramatic showdown in Panama.

Graham Greene's first published novel tells the story of Andrews, a young man who has betrayed his fellow smugglers and fears their vengeance. Fleeing from them, with no hope of pity or salvation, he takes refuge in the house of a young woman, also alone in the world. Elizabeth persuades him to give evidence against his accomplices in court, but neither she nor Andrews is aware that to both criminals and authority, treachery is as great a crime as smuggling.

Trusted by no one, trusting nobody, the Confidential Agent is sent to England. But before his mission has barely begun, he comes face to face with an agent from the other side. As the car he is driving is run down in the fog, a thought strikes him: "It isn't probable - not in England, but it seems to be true, nonetheless - they're going to kill me."

MI6's man in Havana is Wormold, a former vacuum-cleaner salesman turned reluctant secret agent out of economic necessity. To keep his job, he files bogus reports based on Charles Lamb's Tales from Shakespeare and dreams up military installations from vacuum-cleaner designs. Then his stories start coming disturbingly true....