powered by AFI
In 18th-century Spain, the sadistic Marqués Siniestro imprisons a beggar in a dungeon and treats him as a dog, naming him Fido. Ten years later the poor creature is joined by a deafmute servant girl who is being punished for rejecting the marqués' advances. Maddened by his long confinement, the beggar savagely molests the girl and then perishes, a victim of his own metamorphosis into an animal. The ravished girl escapes, kills the marqués, and then tries to drown herself in a river. She is saved by a kindly professor, Alfredo Carido, who takes care of her until she dies giving birth to the beggar's son. Carido christens the child León and adopts him as his own son. As the years pass it becomes apparent that the lad has werewolf tendencies, and by the time he reaches manhood he is responsible for several brutal murders. Realizing the awful truth about himself and fearful that he may someday harm his beloved Cristina, León begs Carido for help. Carido has him sent to a monastery, where he is kept in chains; but eventually León escapes, attempts to elope with Cristina, and is captured and jailed by the police. On the night of the next full moon, León breaks out of his cell and scrambles to the rooftops of the village. The grief-stricken Carido finally kills him with a special bullet--a silver pellet carved from a blessed crucifix.