Nicola catches his wife Sarah cheating on him and, after a violent confrontation, he leaves her. Soon after, Sarah is found stabbed to death with an ice pick. Inspector Terzi is assigned to investigate and suspects Nicola, who is killed soon after. Criminal psychologist Anna Berardi believes Nicola is innocent and suggests that a known maniac, Franco Tribbo, is the real killer, but Terzi is skeptical. Meanwhile, the murders continue.