Tormented by anonymous phone calls and death threats, young Margaret takes a position as secretary to Countess Leonora Moron. After a series of assassination attempts, Mike Dorn of Scotland Yard discovers that Margaret is the daughter of Mary Pinder, who married the Countess's brother, Lord William. Margaret is thus entitled to the inheritance, and Mike realizes she is in grave danger. When Margaret is taken to a mental asylum, she encounters her mother, who spent many years in prison for the alleged murder of Lord William, a crime she did not commit. Mike Dorn manages to free Margaret and discovers that the Countess murdered her brother and that Margaret herself stands in her way...