This is a thrilling murder mystery featuring Sax Rohmer's famous and recurring character Gaston Max. During wartime London, a British lord finds a dead man in his living room. He has no idea about who he is or how he got there. When the police are called and an inquiry begins, Gaston Max shows up and announces that the dead man is a key in his much more important investigation. Several plotlines follow, with a love story, and different suspects are revealed as potential murderers.