At a detective agency in Milan, Carloni (Gino Rossi (actor)) is looking through photographs of an attractive young woman, Paola Molon Fontana (Lucia Bosè), given to the agency by her wealthy industrialist husband, Enrico Fontana (Ferdinando Sarmi). The couple were married seven years ago, shortly after meeting each other. Fontana's recent discovery of these old photos have aroused his suspicion, and Carloni is hired to uncover whatever he can about Paola's life before her marriage. Carloni travels to the town of Ferrara, where Paola spent much of her youth. The detective soon discovers that she was best friends with two girls in town. He goes to the apartment of one of her friends, Matilde (Vittoria Mondello), and learns from her husband that Paola and Matilde's friend Giovanna Carlini died in a tragic elevator shaft fall a few days before she was to be married to Guido Garroni, a local boy with whom Paola had also been involved. When the sullen Matilde arrives home, she refuses to cooperate with Carloni. After the detective leaves, Matilde writes a letter to Guido, alerting him that a suspicious man is investigating Paola's past.