The morning after hearing gunshots in the woods near the land where they work, brothers Pedro and Jaime discover a
disemboweled corpse, which leads them to a nearby shack where María Elena, an elderly woman, and her two sons, Uriel and Eduardo, are in hiding. Uriel has become a "Rotten", a being
possessed by an unborn
demon awaiting physical birth. The corpse was that of a "Cleaner", a professional who was to kill Uriel and exorcise the demon before it could possess others. The authorities dismiss the demon as not their problem. The landowner, Ruiz, suggests removing Uriel from the shack and dumping him away from his land. After driving several hundred kilometers, the men realize that Uriel has fallen off the truck somewhere along the way. Unable to find him, Ruiz declares the matter resolved and returns home. The next morning, one of Ruiz's goats has become possessed. Ruiz's pregnant wife Jimena warns against using guns because they will only spread the infectious possession, but Ruiz shoots the animal with his shotgun. A possessed Jimena then kills Ruiz and commits suicide. That night, Eduardo knocks on Pedro and Jaime's door. Eduardo's mother disappeared after the men took Uriel, and he found Ruiz and Jimena dead. Afraid to return to his shack alone, he begs the men to let him stay the night. Pedro allows Eduardo to sleep in their shed, provided that he surrenders his pistol and promises to leave at sunrise. The next morning, Jaime and Pedro plan to leave town with their families to be safe. Jaime gets their mother Sara while Pedro goes to his ex-wife Sabrina and his two children, Santino and Jair. Sabrina lives with Leonardo, her new husband. The family dog, who previously licked Pedro's demon-mucked clothes, mauls Vicky (Leonardo and Sabrina's daughter) dragging her outside. Leonardo shoots the dog despite Pedro's warning. Pedro returns to Sabrina and discovers that Vicky is back, and seemingly normal. As Pedro steals a car and drives away with his sons, a possessed Leonardo rams his truck into Sabrina and Vicky, who later dances gleefully. After Pedro picks up Jaime and Sara, the assembled family leaves town. They meet up with Mirtha, a former Cleaner and Jaime's acquaintance from the city, who invites them to stay overnight. Mirtha warns Jaime about Jair, who exhibits signs of possession. Jaime dismisses this as related to Jair's
autism. Mirtha explains that they must find and kill Uriel using the appropriate ritual to prevent the demon from being fully born. Sabrina eventually kidnaps Santino. Jaime chases after her while Mirtha and Pedro take Mirtha's truck to search for Uriel. Jaime reaches Sabrina only to find that she has killed Santino and is eating his brains. Furious, he runs Sabrina down and pins her to a tree. Sara stays behind to wait with Jair, who begins walking unassisted and speaking without impediment. Pedro and Mirtha's search leads to a schoolhouse filled with possessed children who killed all the nearby adults and worked to conceal Uriel. Uriel is hidden under an auditorium's stage, and Pedro tries to unearth him as Mirtha sets up the exorcising ritual. Losing his patience and believing that a nearby fire axe might help dismember and move Uriel, Pedro runs to the office only to be locked in by the children. While he is occupied, the children kill Mirtha and dismantle her equipment. Getting back to the auditorium too late to save Mirtha, an angry Pedro beats Uriel to death. The demon is then born out of Uriel's corpse, appearing as a nude, blood-covered child. The demon taunts Pedro, marking him with streaks of blood and sparing his life as he leaves, followed by the children. Pedro and Jaime reunite at Mirtha's house, collect Jair and return home. Inspecting the property, Jaime finds the possessed Eduardo, who admits to killing and eating the original Cleaner four days before. He did the same thing to his own mother and alludes that Sara suffered a similar fate. Inside, Pedro feeds Jair ice cream. However, Jair chokes, and proceeds to cough up Sara's hair and necklace. Pedro walks outside, collapses, and wails. ==Cast==