El Jaro, José Luis Manzano, is a fifteen-year-old with a long criminal record. He visits his older brother in jail, but spends most of his time with his three best friends: El Butano, Jaime Garza, Jhonny, José Luis Yzaguirre, and El Chus, José Carabias. They form a dangerous gang that steals handbags, coins from public payphones, cars and motorbikes, and they also break windows to loot stores. With nowhere to sleep, El Jaro ends up staying with Mercedes, nicknamed La Mexicana, a prostitute twenty years older than him who gives him affection, sex, and a temporary home.
At a cemetery, El Jaro unveils a gun he has managed to obtain, a moment that marks a shift toward bolder criminal acts. This new weapon enables the four friends to escalate their activities as they travel to an upscale Madrid neighborhood to rob a group of gay men. A parallel thread follows a journalist chronicling the harsh realities of unemployment and the connection between poverty and crime in the margins of the city.
While enjoying ice cream, El Jaro nearly gets caught when two undercover policemen spot the gun in his backpack, but Mercedes distracts the officers and saves him. Later, at a disco with his companions, Toñi—Chus’s sister, played by Verónica Castro—catches his eye. Smitten, he invites her for a joyride, though Toñi is more interested in the drugs she uses. To obtain drugs for her, El Jaro turns to El Marques, a drug dealer who supplies him with narcotics after a threatening confrontation. He returns to Mercedes, confessing that he has fallen in love with Toñi, yet their relationship continues.
With Toñi’s help, El Jaro and his gang invade a motel and rob all the clients. In one room, El Jaro discovers his mother, Madre de El Jaro, María Martín, a prostitute he hasn’t seen in years since he was twelve. After leaving the motel, the police pursue them, but the gang manages to escape by dashing across rooftops to a ballet school in the next building. Lara, a detective, is assigned by the commissar to investigate El Jaro’s assault on the motel, and the officers interrogate El Jaro’s mother.
In a bar seeking drugs, El Marques retaliates and his ally, Kid Marin, a gay bartender José Antonio Rico, rapes El Jaro. El Butano mobilizes a large group of teenagers from rival gangs to avenge the assault, leading to a violent confrontation that draws the attention of Lara and the commissar. Refusing to disclose what happened, El Jaro is sent to a reformatory, from which he quickly escapes. At the reform school, a psychologist questions the four friends—El Jaro, El Butano, Jhonny, and El Chus (who is primarily interested in drugs), while a journalist seeks an interview with El Jaro through the judge in charge of his case; before the interview can happen, El Jaro escapes again and is reunited with Mercedes.
On his next outing, El Jaro and his friends are surprised by the police. As they attempt to flee, El Chus is killed and El Jaro sustains a serious groin injury. He awakens in a hospital to Mercedes’s news that he has lost a testicle. After a brief stint in jail, El Jaro rejoins Mercedes, who informs him that Toñi is pregnant. He wants the baby, but Toñi contemplates an abortion, blaming him for her brother’s death. Mercedes intervenes, persuading Toñi to carry the child. Mercedes’s love for El Jaro is sincere, and she promises to care for him and their unborn son.
They flee once more in a stolen car, with police in pursuit as they become a target for four terrorists. In the climactic confrontation, El Jaro and his friends escape as the police and the terrorists fatally clash. He goes to see his mother, who continues to work the streets, and his notoriety in the underworld grows. Sebas, a local pimp, confronts El Jaro in a knife fight, and El Jaro slashes his face. His mother rushes to help her lover as Toñi, increasingly embittered by her forced pregnancy and dependence on Mercedes, confronts El Jaro about living at Mercedes’s expense. He resumes his life of robbery with his friends, and as his son is born, El Jaro is killed by two shots—one to the chest and one to the face—closing the troubled arc of a young man whose crimes defined his fate.
