The novel is set in Cuba in the period immediately preceding the revolution.
The protagonist, a vacuum cleaner salesman (business is bad) and a widower with a fourteen-year-old daughter, is recruited by British intelligence as an agent in Havana.
Enticed by the money, the protagonist fabricates a fictitious network of spies and invents a stream of reports, which are, of course, utterly false.
Given the importance his operation assumes, London dispatches two agents to support him, among whom is Beatrice, with whom the protagonist falls in love.
The narrative unfolds around this paradoxical premise, satirizing the machinery of espionage.
Even when unmasked, the protagonist will be offered a position within the organization, as admitting a mistake is out of the question and, in any case, some grain of truth might still reside in the intelligence provided, blatantly fabricated though it is.
Graham Greene himself placed this novel in the category of "entertainments," and this classification has undoubtedly influenced critics and readers in their interpretation of the book: a mockery of the world of espionage and an indictment, albeit framed as satire, of its tendency to distort reality (a remarkably timely subject).
In truth, if one reads the novel outside this interpretive framework, other thematic layers emerge: the imaginary world forged by the protagonist (a web of spies and false reports) sets in motion a sequence of events, some of them tragic, that destroys the peace and the bonds of friendship that had defined his life.
Furthermore, the latter acts by prioritizing familial devotion (providing his daughter with a prosperous future) over the demands of politics and the values of allegiance to one's country.
What emerges is the contradiction between "genuine" values, formed by friendship and family ties, as opposed to "false" ones

, represented by a sense of belonging to abstract entities, such as the nation and ideologies.
In the epilogue Beatrice, in truth the only genuinely positive character in the novel, explains to her superiors that even had she known, she would not have stopped the protagonist, because

he was working for something important, not for someone's conviction about a global war that might never happen...
and what does one's country mean anyway: a flag that someone invented two hundred years ago."
The most significant limitation, which renders the label of "entertainment" appropriate, lies precisely in the figure of the protagonist, who seems not to realize what he has created, passively enduring events and leaving it to others to create and resolve problems.
This is a passive attitude, which at times renders the novel monotonous and predictable.
The style is highly effective, closely tied to dialogue, with a sentence structure displaying clear cinematic hallmarks: the English is classic.

Our Man in Havana