The Adventure of the Cheap Flat

A glamorous nightclub-singer-turned-spy has stolen the US Navy's plans for a new submarine, and an FBI agent called Burt is in London to catch her. Burt meets Poirot and dismisses him as a gumshoe, while Poirot is not impressed by the self-important G-man. Poirot is drawn into the case when it appears that the submarine plans will fall into the hands of Italy's Fascists unless they are recovered. Then Poirot meets a young couple who have had an amazing bargain on a valuable London apartment, and he sees a connection with the spy case.