A teacher who is having an affair with one of his students takes her out on a boat. They see a knife killing on shore. Other gruesome murders start occurring shortly thereafter, and the teacher suspects that he may be the cause of them.

Already a successful cinematographer working with Sergio Leone on classic westerns, Massimo Dallamano came into his own as a beloved giallo director. Familiar themes of sex and violence are unpredictably reimagined in this chilling thriller, made truly unforgettable by Ennio Morricone’s score.