Overwhelmed by her suffocating schedule, touring European princess Ann takes off for a night while in Rome. When a sedative she took from her doctor kicks in, however, she falls asleep on a park bench and is found by an American reporter, Joe Bradley, who takes her back to his apartment for safety. At work the next morning, Joe finds out Ann’s regal identity and bets his editor he can get exclusive interview with her, but romance soon gets in the way.

A series of murders occur that mirror those committed by the Whitechapel Ripper. Through his experiments with psychoanalysis Dr Pritchard discovers a deadly violence in one of his young female patients. As he delves into the recesses of her mind he uncovers that Anna is possessed by her dead father’s spirit, willing her to commit acts of gruesome savagery over which she has no control. But the most chilling revelation of all is the identity of her father: Jack the Ripper himself.