Vice and Virtue (1963)

1944 : Occupied France. Juliette (Vice) is Wehrmacht General Bamberg's mistress and enjoys a privileged life. Her younger sister Justine (Virtue) is about to marry Jean who is in the Resistance and come to Juliette for help. Both sisters end up at "la Commanderie", where Juliette becomes SS Colonel Schonberg's mistress and Justine is detained with other pretty girls who must satisfy the sexual needs of high-ranking nazi officials. Inspired by "Justine ou les infortunes de la vertu" by the marquis de Sade