This work investigates the complex motivations and operational history of Kim Philby, one of the most significant double agents of the twentieth century. Patrick Seale, a veteran journalist and Middle East expert, utilizes extensive interviews and archival research to reconstruct Philby's trajectory from his recruitment at Cambridge to his eventual defection to the Soviet Union. The book argues that Philby's ideological commitment to communism, rather than mere opportunism, served as the primary driver for his decades-long betrayal of British intelligence.

Experts frequently cite this work as a definitive biographical account of Philby's life and career. Readers often note the detailed, journalistic prose style that provides significant insight into the psychological profile of a high-level intelligence operative.