Il terzo occhio (1966)

Young nobleman Mino lives with his mother and Marta, the housekeeper, in an old, decaying castle. He is infantile and morbidly attached to the weird duo; his only hobby is taxidermy. Laura, Mino's fiancee, is met with jealousy and hatred by the two women, and decides to leave the castle; but Marta sabotages her car brakes and she is killed. Mino takes her body back to the castle. Meanwhile, his mother is violently arguing with Marta, who throws her down the stairs and repeatedly bashes her head on the floor. The distraught Mino descends into madness: he picks up a stripper at a nightclub and brings her home, then strangles her while having sex next to Laura's dead body. He does the same with a prostitute. Marta discovers these murders and offers to help dispose of bodies. A year later, Daniela (Laura's twin sister) arrives at the castle...