Elisabeth Thorpe, code-named Cynthia, was a glamorous American recruited by MI6 to obtain intelligence from the Polish Foreign Ministry, then from the Italian and Vichy French Embassies in Washington. Her method was to seduce whatever targets could provide her with vital intelligence, a practice in which she hardly ever failed, enabling her to secure first the Italian then the Vichy French naval codes. In the landings in North Africa, she was credited with having saved the lives of many Allied soldiers.

This unique account by a British spymaster of his relationship with her, of his subsequent involvement with Philby and the Cambridge spies and dealings with his counterparts in the CIA and French intelligence, was entrusted by him to a junior colleague on the basis that it was not to be published until everyone in it was dead. Necessarily anonymous and impossible fully to verify, most of it undoubtedly did happen and is part of the historical record, providing a special insight into the world of intelligence and one of its greatest practitioners, Cynthia.