A medieval nun is caught in the struggle between her religious vocation and her repressed sexuality. As her abstinence drives her towards madness, she is touched by a terrifying vision of death and also imagines the figure of Mary Magdalen, who challenges her preconceptions about sex as an evil force. Then, as she broods over her fate, the nun's mind is flooded with violent sexual imagery and she gradually make her way towards the brink of self-destruction.