Six years have passed since the Beresfords first began their sleuthing partnership and marriage in 'The Secret Adversary’. Tommy now has a desk job with the British Secret Service, and Tuppence is at home. But when the chief of British Intelligence calls upon them to take over the International Detective Agency, which has been a tool of the Bolsheviks involved in spying activities, both are ready for a new adventure. Tommy poses as Mr. Blunt, the former head of the agency, incarcerated for espionage, and Tuppence masquerades as his secretary.