A struggling vacuum cleaner salesman is recruited into the world of British intelligence, only to find his fabricated reports manifesting as dangerous reality. James Wormold, a man living in Havana with his expensive-tasting daughter, accepts a recruitment offer from a mysterious intelligence officer to secure extra income. Tasked with providing reports on local activities, he begins inventing sources and data to satisfy his handlers. The narrative follows his descent into a web of his own making as his fictional intelligence begins to mirror actual events, forcing him to navigate a landscape of shifting loyalties and lethal consequences. The story is presented through a third-person perspective that emphasizes the absurdity of bureaucratic incompetence.

Readers and critics frequently highlight the sharp, ironic tone that defines this work as a classic of the espionage genre. Discussion often centers on the effectiveness of the satire, which mocks the rigid structures of intelligence organizations through the lens of an amateur spy. Many note that the pacing is deliberate, favoring character development and atmospheric tension over high-octane action. The balance between the protagonist's personal struggles and the broader political stakes is often cited as a key strength of the narrative. Ultimately, the book is recognized for its ability to transform a farcical premise into a commentary on the dangers of institutional self-deception.