Hell Penitentiary(1984)

Original title: Detenute violente

When her sister turns up dead, Julia (Linda Jones) tries to convince the cops that a notorious gangster is to blame by going undercover as a prisoner to unearth the only witness to the crime. Problems arise when the sexually perverse warden (Rita Silva) adopts Julia as her new plaything and throws her noble mission off-course. Ajita Wilson and Alessandro Freyberger co-star in this erotically charged thriller.