Lust, sorcery and torture - the secrets of a Spanish monastery. Ambrosio, a pious monk, finds himself drawn to his pupil, Matilda, a young woman in disguise. Unable to control himself, he sates his lust, and soon tires of her. But Matilda has more than her body to offer: using black magic, she will help Ambrosio seduce the innocent Antonia. As his desperate acts become more and more depraved, it becomes clear that Matilda is not everything she seems. And Ambrosio's damnation may be closer than he feared...