After a rare gem is stolen from an exhibition at a posh hotel, Inspector Farraday decides to recruit former thief Boston Blackie to find the stone. Along with his assistant, "The Runt", Blackie focuses his investigation on the hotel manager, George Daley, and his sister, Eileen. Through disguises and ruses, Blackie and the Runt try to trick their way to discovering the thieves.

In Africa early in World War II, a British rubber plantation executive reminisces about his arrival in the Congo in 1910. He tells the story of a love-hate triangle involving Harry Witzel, an in-country station superintendent who'd seen it all, Langford, a new manager sent from England for a four-year stint, and Tondelayo, a siren of great beauty who desires silk and baubles. Witzel is gruff and seasoned, certain that Langford won't be able to cut it. Langford responds with determination and anger, attracted to Tondelayo because of her beauty, her wiles, and to get at Witzel. Manipulation, jealousy, revenge, and responsibility play out as alliances within the triangle shift.