Francisca de la Cruz, a wealthy orphan, and Mariana de Castro, her widowed Protestant friend, live in a town where they are the center of hostile gossip. Father Francisco Verdugo, the Inquisitor, has his own ambitions. He has his greedy eyes on the orphan heiress' properties, but he needs a pretext to steal them. A confrontation in the street between a group of girls gives him the perfect excuse to arrest Mariana and Francisca and enchain them in the horror chambers of the Inquisition, leading them to a frightful end as they are convicted of witchcraft.