In Victorian London, Edward Styles is accused of being the notorious Haymarket Strangler, the brutal killer of five women. Twenty years after he is tried and executed for these crimes James Rankin (Karloff), a novelist and social reformer, launches an investigation to prove that Styles is innocent. His search for clues leads him first to the sleazy Judas Hole music hall, where the Strangler picked his victims from the resident can-can dancers and loose women, and then to the prison cemetery of Newgate where Styles was buried - in order to exhume his body. When the killings start again, Rankin's theory seems to be vindicated. However his growing obsession with the case signals a most unwelcome revelation as to the true identity of the murderer.