On the outskirts of a bustling favela, Pietro and Cristian embark on a dangerous journey that begins with a simple act of defiance. While fishing by the shore, they retrieve a crucifix from the ocean, and during this moment, Cristian experiences a seizure, prompting Federica Torchetti's character, Sanghe slug, to come to his aid. Pietro reveals that they have been tasked by the Ants, a ruthless gang primarily composed of children, to set fire to a local pet store called Mondocane — a nickname meaning “Dog World.” Under cover of darkness, the boys carry out the arson together, marking the beginning of their immersion into the perilous world of gang violence.
Their actions attract the attention of Katia, a dedicated police officer played by Barbara Ronchi, who begins to investigate the case. Her interviews lead her to Sabrina, a young girl played by Ludovica Nasti, who admits to sneaking out of her orphanage to visit the pet shop. It is revealed that Katia herself was raised in that orphanage, adding a personal layer to her commitment to bring justice.
Pietro is brought before Hothead, a formidable gang leader. He insists on Cristian being allowed to join the gang as well, despite Cristian’s seizures which make him undesirable in the eyes of the Ants’ members. When the gang rejects Cristian, Pietro is left devastated, especially after they lose the old man they live with, who suddenly passes away. With the crucifix as their symbol of hope, Pietro and Cristian set out to find the Ants once more. Their quest leads them to witness children being rounded up by police, and ultimately they are captured by the gang after an intense encounter. The Ants accept Cristian into their fold on the condition that they assist in a burglary. Inside a wealthy home, Cristian boldly confronts the homeowner, revealing her hiding in a closet. Her refusal to give up the safe’s combination earns her a tense punishment, but both boys are finally inducted into the gang.
As their involvement deepens, Pietro and Cristian venture to a wealthy beach frequented by the city’s elite, where Sabrina is working. Recognizing the boys, she makes them swear secrecy if they promise to visit her at her parents’ grave, located in a restricted area. The boys agree, sealing a fragile alliance built on shared hardship. Soon, they are involved in a violent mission to eliminate a former gang traitor. While guarding motorcycles, they sneak closer and witness Cristian shooting the escapee, hinting at internal tensions within the gang. During the celebration, Hothead confronts Cristian privately, accusing him of not firing the weapon, a suspicion that shadows the gang’s unity.
The story intensifies as Pietro and Cristian return to their familiar beach spot, where Sabrina is waiting. Cristian heads back to the hideout, while Pietro visits the grave of Sabrina’s parents. On his return, Pietro learns that another gang member was captured by police, leading to a brutal interrogation. Katia questions the captured gang member, who later escapes and tragically leaps to his death. Hothead, enraged, orders Pietro to prove his loyalty by eliminating Katia. Pietro prepares to shoot her but hesitates upon seeing Sabrina in her car, recognizing her from previous encounters. Instead of firing, he allows the police to open fire on both Katia and his own car, leading to her death. Pietro and Sabrina narrowly escape to the ocean, fleeing the chaos.
The Ants pursue them, eventually cornering the pair at the docks. Sabrina manages to escape by boat, while Pietro seeks refuge in a warehouse. When Cristian finds him, their confrontation is interrupted by Cristian’s epileptic seizure. Mistaking Pietro for Cristian in the chaos, Alessandro Borghi's character, mistakenly believed to be Cristian, is shot dead by Hothead. Pietro, overwhelmed by betrayal and violence, shoots Hothead and escapes. He then climbs onto a train, disappearing into the horizon as the film concludes, leaving his future uncertain but free from the violence that has consumed his life.
