The beautiful prostitute Ulla (Edwige Fenech) is hired by the despicable Mudy (Maud de Belleroche) and invited on a sea cruise where Ulla is meant to take the virginity of Mudy's son Tony, a shy and mentally disabled 20-year-old with a tendency toward pyromania. Also invited on the cruise are the provocative Paula (Rosalba Neri) and her husband Aldo (Bonuglia), who are constantly striving to win the favor of a wealthy woman in hope of obtaining an oil concession. Despite her efforts, Ulla has no effect on the young man until the yacht stops on a Mediterranean island inhabited only by a goat herder and his wife, Beba (Eva Thulin). Tony is attracted to her, but little by little his mental disorders arise, and the story ends in tragedy.