Francis (John Kerr) decides to pay a visit to his lonely brother in law Nicholas Medina (Vincent Price) in Spain after hearing about the sudden death of his sister, Elizabeth (Barbara Steele). Upon his arrival at the grand castle, Francis is clearly unwelcome by his lunatic brother in law. Elizabeth's mysterious death has raised question for Francis which made him wanting to investigate further the reasons behind her sudden and untimely death. Meanwhile, Nicholas has been hearing Elizabeth's voice calling out his name and believes that she has been buried alive. Elizabeth is in fact still well and alive as she concocts a devious scheme unwitting to anyone, together with her lover named Dr. Leon (Anthony Carbone) by making sure he is pushed to the brink of madness and in the end she being able to inherit his wealth.