In 1937, Republican Militia force a circus troupe to fight on their side in the Spanish Civil War. The Funny Clown (Santiago Segura) slaughters dozens of Nationalist troops, armed only with a machete, before being shot and disarmed. While his fellow troupe members are executed, the Funny Clown is sentenced to work as a slave laborer, at the monument of the Valle de los Caídos. His son, Javier (Sasha Di Bendetto) tries to free him by setting off dynamite where he was working. But Colonel Salcedo (Sancho Gracia) tramples the Funny Clown to death with his horse. Javier knocks him down, gouging out his eye in the process. Salcedo vows to remember Javier for this insult.
In 1973, Javier (Carlos Areces) joins a circus as its sad clown, as he has never been able to make children laugh. His counterpart as funny clown is Sergio (Antonio de la Torre), an arrogant, crude, violent man who admits that were he not a clown, he would probably be a murderer. Javier begins to fall in love with Sergio's girlfriend, the trapeze artist Natalia (Carolina Bang). After Sergio becomes enraged when Javier refuses to laugh at his jokes at dinner one night, Sergio beats Natalia unconscious then storms out. Javier encourages Natalia to leave Sergio, but when Sergio returns she engages in rough anal sex against a window while Javier cowers below. She later tells Javier that she is sexually and emotionally attracted to Sergio's violent nature.
Sergio admits that Javier is an excellent sad clown but grows suspicious about his attention to Natalia. In fact, Natalia has encouraged Javier to develop feelings for her, as she was impressed by his refusal to laugh when Sergio told him to. They begin to see one another behind Sergio's back. One night, at an amusement park, Natalia admits she has begun to love Javier as well and kisses him tenderly. Sergio suddenly appears and beats them both savagely; Javier's wounds land him in the hospital. Natalia tells Javier they must never see one another again for his sake. After having a dream in which Sergio foils his repeated attempts to rescue Natalia from various situations, Javier escapes from the hospital and returns to the circus. Despite the efforts of the other troupe members to stop him, Javier finds Sergio and Natalia having sex. Now insane, Javier beats Sergio mercilessly in the face with a trumpet, leaving him mauled and near death. As Javier escapes through the sewers, the circus troupe takes Sergio to the closest doctor – a veterinarian – for medical care. The doctor is able to save Sergio, but his face is horribly scarred with a glasgow smile. The circus is forced to close down. Natalia and several of the other troupe members become performers in a nightclub.
Javier lives in the forest, naked and covered in filth. He survives on wild animals that fall into his cave. One day he is captured by hunters – including Salcedo, who recognizes him. Salcedo forces him to behave as a hunting dog but ultimately intends to kill him. At one point Javier viciously bites none other than Generalísimo Francisco Franco, one of Salcedo's guests. As a consequence he is locked in a room while Salcedo plans exactly how to kill him. Javier has a vision of Natalia, as the Virgin Mary, ordering him to become her Angel of Death. He scars his face with sodium hydroxide and a clothes iron to make it look permanently like that of a clown, then dons a clown's costume patterned after a bishop's vestments. He then kills Salcedo and escapes into the city.
Afraid that Sergio intends to harm her, Natalia prepares to leave the nightclub. But Sergio and Javier both arrive at the same time, Javier armed with machine guns. Forced to choose between them, Natalia chooses Sergio, and they drive away together. Police try to arrest Javier, but some of the remaining troupe members help him escape. Repulsed by Sergio's mauled face and crude ways, Natalia leaves him again. Javier steals an ice cream truck and stalks her through the city. He uses the occasion of ETA's successful attempt on Admiral Carrero Blanco (Franco's heir apparent) to kidnap Natalia. He takes her to the Valle de los Caídos, hewn from rock, where the circus has kept its animals since going out of business. There he pleads with her to love him for his mind and body as much as she loved Sergio for his. At first she refuses but admits she no longer loves Sergio.
Sergio, meanwhile, has learned of Javier's hideout. He informs the military police, which has been looking for Javier in connection with the terrorist bombing, and accompanies them on their attempt to arrest him. Sergio puts on his clown make up and chases Javier and Natalia through the Monumental Cross at the Valle de los Caídos where they climb to its highest point, several hundred feet off the ground. Natalia admits her love for Javier and suggests they escape by wrapping lengths of drapery around their waists and lowering themselves to the ground. Before this can be accomplished, Sergio arrives and fights with Javier. Distraught over the continued violence, Natalia leaps from the ledge; rather than getting to the ground safely, she is killed instantly when the drapery draws taut around her waist and snaps her spine.
The military police place Sergio and Javier in custody. As they sit opposite one another, the Funny Clown and the Sad Clown crying so hard as to appear they are laughing.Carlos Areces as Javier
Carolina Bang as Natalia
Antonio de la Torre as Sergio
Manuel Tallafé as Ramiro
Alejandro Tejería as Ghost Rider
Manuel Tejada as Ringmaster
Paco Sagarzazu as Anselmo
Santiago Segura as Clown
Fernando Guillén Cuervo as Military captain
Sancho Gracia as Coronel Salcedo
Enrique Villén as Andrés
Gracia Olayo as Sonsoles
Raúl Arévalo as Carlos
Joxean Bengoetxea as Millionaire
Terele Pávez as Dolores
Juana Cordero as Mum
Joaquín Climent as Dad
Luis Varela as Veterinary
Fran Perea as National Soldier
The film received positive reviews; it currently holds a score of 77% on Rotten Tomatoes with the consensus being that the film was "an uneven but winningly insane blend of hard violence, sex, black humor, and social satire."
Cole Abaius wrote that "Over all, the film is incredible. In the oldest sense of that word, it is awe-inspiring and grotesque. Stunning and heartfelt. It is a love letter to a country, a time and a frowning clown singing mournfully about a weeping trumpet."
At the 67th Venice International Film Festival the film was nominated for the Golden Lion and Álex de la Iglesia received the Silver Lion award for Best Director.