It was adapted into a film of the same name in 1959, directed by Carol Reed and starring Alec Guinness.
The novel is set in Cuba during the regime of Fulgencio Batista (which was to be overthrown by Castro). James Wormold, a vacuum cleaner salesman, meets Hawthorne, who offers him work for the British secret service. Wormold's wife has left him for another man and he lives with his teenage daughter, Milly. Since Wormold does not make enough money to grant all his daughter's wishes, he decides to take the offer. For lack of any real information to send the secret service, Wormold begins to deceive them by claiming that he has a network of agents. He carries his reports to extremes by sending his clients in London sketches of parts of a vacuum cleaner, telling them that these are sketches of a secret military installation. In London nobody except Hawthorne, who alone knows that Wormold sells vacuum cleaners, doubts this report. Nevertheless Hawthorne does not tell his boss about his doubts for fear of losing his job.
Rob's rating for the movie: 7.0 of 10.
For more on the subject, see The Best Indian Movies.