Back from the Dead (1957)

When Katy Hazleton visits her sister, Miranda/Mandy, and her husband, Dick Anthony, Dick tells her of his concern over Miranda's recent moody and strange behavior. Walking along the beach that night, Miranda hears strange voices, and when she returns home, becomes hysterical and falls into a coma. When she recovers, she is hostile and claims she is Felicia and not Miranda. Dick tells Katy that Felicia was his first wife, who died in a plunge from a cliff. Miranda asks to see Mr. and Mrs. Bradley, parents of Felicia, and when she calls Ada Bradley "mother", Dick and Katy realize she is possessed by "the other one." Ada Bradley has been practicing black magic for six years and believes it is responsible for returning her dead daughter to her. Mr. Bradley, as one would expect, is horrified at both revelations, although the first one indicates he wasn't paying much attention to what his wife was doing when she was puttering around the kitchen the past few years. That night "Felicia" tries to kill Katy by flooding her room with gas, but Katy awakens in time. Both of the Bradleys suffer strokes - long odds, not impossible - that night and the old man dies while Ada is left paralyzed. The desperate "Felicia" seeks out Maitre Renall, also a black practitioner but on a grander scale than Ada Bradley, as the only person that can keep her alive. He promises to do so but only if she will make a blood sacrifice of an innocent victim. Nancy Corodell, jealous of Renall's attention to "Felicia", hears this and Renall's black magic gets tested by the hell-hath-no-fury method.