The homicidal maniac,who is strangling young women in London's West Side, is being sought by both Scotland Yard and a young reporter/writer, Penny Sutton. She had found one of the murder victims and had set out to get the story for both her newspaper, and for the thriller yarns she writes. The trail leads to an eccentric millionaire living under an assumed name. Penny uncovers enough evidence to convict the man, but a new clue turns up in time to save him and unmask the real killer.