On the Italian coast, writer Paul Decker (Peter Van Eyck), who has grown unhappy in his marriage, executes what appears to be a perfect murder of his wife. Although Paul is believed to be writing a book in France, his stepdaughter, Candy (Mandy Miller), is sure that he murdered her mother, and suspects he also murdered her father years before. With the police unwilling to investigate any further, Candy sets out to confirm her suspicions and take Paul down herself.