In Spain, Leon is born on Christmas day to a mute servant girl who was raped by a beggar. His mother dies giving birth and he is looked after by Don Alfredo. As a child Leon becomes a werewolf after having been taken hunting. As a young man, he works in a wine cellar and falls in love with the owner’s daughter Cristina. One full moon, he again turns into a werewolf and terrifies the town.
In Spain a cruel and arrogant Marques is wedding a young and beautiful maiden. During the elaborate celebration a beggar appears. After making fun of him, the marques gives the beggar some food and then has him thrown in the dungeon.The beggar becomes friends with the jailer and his young daughter. After the jailer died, the mute girl of his grows up to be a beautiful and voluptuous woman. The marques, now an old and disgusting looking widower, makes sexual advances toward her and she bites him and runs off. He then finds out who she is and has her thrown into the dungeon until she changes her mind about his advances. The beggar now is old and has gone completely mad. Shortly after she is thrown in with him, the beggar rapes her. She is let out and the marques pulls his old tricks again until she stabs him to death. The young mute ran until she passed out in a distant forest and was found by a kind man. He and his wife take care of her until she has the beggar's baby. The problem is that he is born on Christmas Morn at Midnight. That bears an awful curse that takes her life and causes her baby son to wear the mark of the beast. Years later, the young boy, still being raised by the couple, escapes their home some nights. On those nights, live stock is always slaughtered by a powerful beast. The couple finds out that it is Leon, their adopted son. A local priest tells then that he is a werewolf and that only love can calm the savage beast. The couple heeds the priest's advice and love keeps the beast at bay. Until that is, when Leon becomes a man and moves away for work. He falls for a young lady but then the beast takes over and Leon's demon emerges and starts to kill his fellows and his loves interest's fiance. As the death toll rises, the other prophecy of the priest comes true. "Whatever weakens the spirit will strengthen the wolf" .Finally, the hunter becomes the hunted, and Leon, the werewolf is killed, and killed by his own father.