Adapted from Graham Greene's novel, Alec Guinness stars in this classic spy spoof as Jim Wormold, an English expatriate who sells vacuum cleaners in Havana.

His life is irrevocably changed as he is recruited by Hawthorne (Noel Coward), and pressed into service as an operative of M.I.5, which he reluctantly agrees to so he can earn extra money for his 17-year-old daughter.

Wormold does not actually engage in any actual espionage. Instead, he invents facts on his reports and recruits fictitious agents. However, these reports are taken seriously in London and two additional agents, a radio operator and a secretary (Maureen O'Hara), are despatched to assist Wormold.

He soon discovers that his imagination is going to take on a life of its own...