Cruel Passion (1977)

Two sisters are expelled from a nunnery and are plunged into a life of debauchery. While one embraces her new lifestyle, the other is desperate to cling to her old morality and sees a hope of salvation in a mysterious aristocrat who harbours a hidden dark side. Historical drama based on the novel Justine by the Marquis de Sade, starring Koo Stark and Martin Potter.