Disabled countess Federica Donati (Isa Miranda) is strangled to death by her husband, Filippo Donati (Giovanni Nuvoletti). Filippo is subsequently stabbed to death by an unseen assailant, and his body is then dragged to the bay beside their mansion. The police investigate and find a suicide note written by the countess, but do not discover Filippo's murder. Real estate agent Frank Ventura (Chris Avram) and his lover Laura (Anna Maria Rosati) are plotting to take possession of the bay. When the Countess refused to sell her estate to them, the couple conspired with Filippo to murder his wife. The pair are unaware that Filippo is dead and cannot proceed with their scheme without his signature. Meanwhile, four local teenagers Duke (Guido Boccaccini), Bobby (Roberto Bonanni), Denise (Paola Montenero) and Brunhilde (Brigitte Skay) break into the seemingly deserted mansion, looking for fun. However, they are soon killed one by one. Are all these events connected?