The Day of the Beast

Ángel Berriatúa, a Basque priest and professor of theology, confesses to another priest that he intends to commit as much evil as he can. The other priest is shocked until Ángel whispers his reasoning. When the other priest agrees to help him, a large cross falls and crushes him.
Ángel goes into downtown Madrid, committing various sins and crimes such as taking money from a homeless man, pushing a street performer over, and telling a dying man to go to Hell and stealing his wallet. He goes to a record store and meets José María, a self-described Satanist and heavy metal fan from Carabanchel, who gives him a tape of the most "evil" band he can think of. José María puts Ángel up in his mother's boarding house where he lives with his mother, grandfather, and Mina, a woman he is attracted to who helps his mother with the business. Ángel then attempts to steal a book written by occult TV show host Professor Cavan, convinced it can tell him how to sell his soul to Satan, believing that a secret code in the Bible says that the Antichrist will be born at midnight on Christmas Eve. He intends to sell his soul before the night is out to get into the birth ceremony and kill the Antichrist. The store manager does not believe him and he flees.
Ángel and José María team up to kidnap and tie up Cavan, who they intimidate into telling them how to complete the ritual, which requires the blood of a virgin. Ángel first tries to get it from Cavan's girlfriend Susana, but after knocking her out by mistake, Cavan admits that she is not a virgin. Ángel then goes back to the boarding house to try with Mina but José María's mother sees him and tries to kill him with a shotgun. Ángel escapes with some of Mina's blood, but accidentally kills José María's mother. Ángel, José María, and Cavan are able to burn a piece of paper, take LSD, and complete the ritual, which Cavan believes is made up. However, a he-goat appears in the room and then disappears. Ángel then finds a message in the burnt scraps of paper in which the devil taunts him, not fooled by Ángel's actions. Ángel, José María, and Cavan flee the apartment when the police arrive on suspicion of Cavan's kidnapping.
Ángel and José María frantically drive around town looking for a sign to point Ángel in the right direction. Ángel first tries to get the information on the birth of the Antichrist out of a man giving a speech about the predictions of Nostradamus, resulting in a chase in which three men dressed as the Three Wise Men are shot by police by mistake. He then tries to find the information at a heavy metal show, but is beaten up by the attendees. Cavan goes on television and asks Ángel to call him, telling him that he's realized Ángel was right and he knows where the birth of the Antichrist will be.
Cavan points out that the devil uses his own markings, similar yet opposite to the Christian cross, in order to mock God, and points them toward a pair of buildings in the same shape of the devil's mark: the Gate of Europe. The three men engage in a fight with an extreme-right gang that has holed up there and has been seen throughout the film murdering homeless people and spray painting Limpia Madrid (transl. clean up Madrid) everywhere. Their leader is revealed as the devil when he throws José María off the building to his death. The gang beats Cavan badly, but Ángel gets hold of a gun and kills the gang, which was also killing a baby who is the Antichrist. He then shoots the devil as well.
Some time later, another actor takes over Cavan's show, and Ángel and Cavan become homeless drifters; while Cavan constantly complains that they will never be able to tell anyone how they saved the world, Ángel simply misses José María, but has accepted the events as the duo's fate.