Giles Denison wakes up in an unfamiliar hotel room to discover his identity has been stolen and replaced with that of a prominent scientist, thrusting him into a high-stakes international conspiracy. Denison must navigate the treacherous landscape of Cold War Europe, assuming the role of Dr. Harold Feltham Meyrick to survive the machinations of his captors. He faces constant surveillance and the threat of exposure as he travels from Norway to the Soviet Union, forced to interact with the scientist's family and associates. The narrative maintains a relentless pace, utilizing a third-person perspective to track Denison's desperate attempts to reclaim his life while evading those who seek to exploit his new identity.

This novel is frequently cited as a quintessential example of the Cold War thriller genre, noted for its technical precision and focus on the mechanics of espionage. Readers often highlight the plausibility of the protagonist's predicament, which grounds the high-concept premise in a realistic, gritty atmosphere. The narrative structure is praised for its ability to maintain suspense through constant shifts in location and the psychological strain placed on the lead character. It stands as a representative work of its era, reflecting the anxieties of the time through a lens of calculated, fast-paced action.