The book is a satirical espionage novel set in pre-revolutionary Cuba, where a hapless vacuum cleaner salesman is recruited by British intelligence to serve as their operative in Havana. Despite his lack of experience and qualifications, he fabricates intelligence reports to appease his superiors, inadvertently triggering a cascade of increasingly absurd and dangerous events. As the line between fiction and reality blurs, the protagonist finds himself entangled in a web of deception and political intrigue that satirizes the absurdities of the Cold War era and the follies of intelligence agencies.

The book is a fictionalized account of the life of Fray Servando Teresa de Mier, a real-life Dominican friar from the 18th century. It follows his numerous escapes from colonial authorities across Latin America and Spain after he delivered a controversial sermon in Mexico City. The narrative, infused with magical realism, portrays Fray Servando's adventures and misfortunes as he becomes a symbol of freedom and resistance against oppressive regimes. His journey is marked by a series of bizarre and fantastical encounters, reflecting the author's critique of totalitarianism and exploration of the themes of liberty, identity, and the absurdity of political persecution.