A mild-mannered physicist is thrust into a dangerous international conspiracy after a head injury convinces him he is a seasoned secret agent. Henry Barstow, a quiet academic, finds his holiday interrupted by an arms manufacturer who lures him into the volatile political landscape of Ixania. Following a physical trauma that induces a dissociative identity, Barstow assumes the persona of Conway Carruthers, a man of action and intrigue. He must navigate a web of geopolitical instability and sinister agendas while struggling to discern reality from his own fractured perception. The narrative unfolds with a focus on the tension between the protagonist's intellectual background and the high-stakes environment of Eastern European espionage.

This novel is recognized as the foundational work that established the modern espionage thriller genre. Critics often highlight how the story subverts traditional spy tropes by placing an ordinary, confused academic at the center of a lethal political game. The work is noted for its early exploration of the moral ambiguity inherent in the international armaments industry. Readers frequently observe that the protagonist's psychological instability serves as a clever device to heighten the suspense and unpredictability of the plot. The book remains a significant entry in the author's bibliography for its role in shifting the thriller toward a more grounded and cynical realism.