Inspector Marney of Scotland Yard travels to Calcutta to investigate the murder of Leonard Lee, a generally despised man in these parts. John Wales, who did consider Lee a friend - his best friend - is a suspect, but he proposes to the Inspector a ploy to discover the identity of the murderer: hold a séance conducted by a medium, Madame Rosalie La Grange. Wales doesn't believe Mme. La Grange will discover the murderer's identity through such hocus pocus, but does believe the process might draw out the murderer in revealing him or herself. Wales invites who he considers suspects - generally those in the upper crust of British society in Calcutta - plus a few red herring attendees so as not to tip the murderer as to the séance's purpose. Upon Mme. La Grange's arrival, she does admit that most of her work is conducted as parlor tricks solely for sheer entertainment, but that when required, she truly does have the ability. As the course of the evening progresses, Mme. La Grange turns from medium to detective as she truly does try to figure out the identity of the murderer, albeit for ulterior motives.