Greta, the Mad Butcher(1977)
Greta a vicious warden, runs a mental-hospital for young women. A girl deliberately "checks" in to the hospital to find out what has happened to her sister who stayed there. Meanwhile Greta and one of the guards are forcing the inmates to have sex with male prisoners, filming them and selling the recordings as pornoflicks.
Directed by Jesús Franco - With Dyanne Thorne, Lina Romay, Jesús Franco, Tania Busselier, Peggy Markoff, Esther Studer, ...