Ruth Rogen goes to the electric chair for strangling her three lovers before she can exact revenge against a fourth, quack spiritualist Paul Bavian, who turned her in to the police. Before she is electrocuted, however, Dr. Carl Houston, an eminent psychologist who believes in transubstantiation, gets her permission to experiment with her body after she is dead. Houston believes that after its host dies, an evil spirit can pass on to another living being. While Houston experiments on Ruth, John Courtney, an heir to millions, dies, leaving his twin sister Roma sole possession of the Courtney fortune. Bavian, hoping to acquire her money, contacts Roma, claiming he has been in touch with her dead brother, who is anxious to give Roma a message about his death. Bavian's landlady, a poor, drunken busybody, blackmails Bavian for half the Courtney fortune and he kills her with his poison ring. Roma's suitor, Grant Wilson, believes Bavian is a charlatan, but accompanies Roma to a seance. During the seance, John's face, in reality a mask that Bavian has constructed, appears and accuses Nick Hammond, the manager of the Courtney estate, of murdering him for money. Following the seance, Grant and Roma interrupt Houston's experiments with Ruth's corpse, and Ruth's spirit tries to enter Roma's body. Skeptical about Bavian, Grant arranges a seance at the Courtney home with Houston and Hammond in attendance. Once again, through special effects, Bavian convinces Roma she is seeing her brother, and John again accuses Hammond of murder. In the confusion following the seance, Bavian pricks Hammond with his ring and he dies. Ruth's spirit then enters Roma's body, and Roma leaves with Bavian in order to kill him. After visiting Ruth's old apartment, Roma leads Bavian to the Courtney yacht, where he readies himself for seduction while Roma readies herself for murder. Grant and Houston follow the couple to Ruth's apartment and realize Ruth has possession of Roma's body. John's spirit helps Grant think of the yacht, and he arrives in time to keep Roma from strangling Bavian, who is trying to prick her with his poison ring. Bavian, terrified, hangs himself while trying to flee the boat, and Ruth's spirit vanishes. When Roma wakes with no memory of the night's events, Grant lovingly tells her he shanghaied her onto the yacht. John's spirit then enters and blows open a magazine, which says "go to Bermuda for your honeymoon."