La settima donna (1978) by Franco Prosperi
aka: The Last House on the Beach, Terror

A Midsummer Night’s Dream turns into a horrible nightmare, when three bank rubbers invade and terrorise the idyllic sea side weekend residence of four young girls and their teacher, Sister Christina (Florinda Bolkan). Taking advantage of their education and innocence, the three intruders soon enough, but still too late for some of the girls, have to face a different side of the peaceful and devoted sister.

seen at: pickledfeet private videothek