A priest with a haunted past and a novice on the threshold of her final vows are sent by the Vatican to investigate the death of a young nun in Romania and confront a malevolent force in the form of a demonic nun.

Years ago, a cruel and merciless nun turned a boarding school into a living hell for her students until they could no longer bear the abuse, and she mysteriously disappeared. Now the alumnae are being brutally murdered one by one.

In eighteenth-century France, a girl is forced against her will to take vows as a nun. Three mothers superior treat her in radically different ways, ranging from maternal concern, to sadistic persecution, to lesbian desire.