At the beginning of the movie, brothers Pedro and Jimmy hear gunshots coming from the nearby woods. The next morning, they grab their rifles and, accompanied by their dogs, venture into the woods to investigate. There, they stumble upon the remains of a man, only half of his body remaining.
They also find some other objects nearby, and Jimmy says he has seen this somewhere, but he doesn't know what it is. Pedro also discovers a map inside the bag and informs Jimmy that the man was using a shortcut leading to Maria Elena's house, and they also find a copy of Maria Elena's ID in it. They both go to Maria Elena's house, and Jimmy asks her if she heard the gunshots last night?
Pedro tells her about their discovery and asks her if she was waiting for someone? because he won't make it. Maria says they were waiting for him, so that he could deal with her son Uriel.
Pedro enters the room to check on Uriel and is stunned by his condition. Uriel's brother reveals that he's possessed and has been rotting for some time. Maria blames herself, thinking that praying would heal him.
Pedro, angrily says that the churches are dead, and Uriel's brother adds that they were afraid of being evicted from their land by Ruiz and the neighbors. Both of them head directly to the police station, but the superintendent refuses to acknowledge that Uriel is possessed and claims it's not their concern. Prado becomes furious upon hearing this and informs the superintendent that they discovered the cleaner's dismembered body.
The superintendent says there's a protocol for cases like this and asks them to do whatever they want to. After this they meet Ruiz and tell him about this and that even the police and the mayor are not doing anything about it. They even asked them not to speak, or they would be marked a ghost town.
Uriel shares that his four dogs disappeared a month ago, and they say that the presence of these entities seems to affect both animals and the deceased. Pedro proposes the idea of auctioning off their possessions and leaving before it goes viral. However, Uriel says it was a setup by the state as they want his land, and that's why they abandon them.
That night, Ruiz goes to Maria's house in anger and is about to shoot Uriel, but Maria requests him not to finish evil like that, or the evil will take their bodies and their souls. She says it has to be done by a professional. Uriel provokes Ruiz to end his life before he possesses the life growing inside of his wife Jimena.
The following day, Jimena arrives with Pedro and Jimmy. Pedro tells Ruiz that they have to leave, but Ruiz insists that Uriel must go, and they need to take him as far away as possible. Pedro expresses his concerns about the risk involved, but Ruiz is determined and insists that he will undertake this alone, because the rotten must be removed from his land before it rots the rest.
Pedro and Jimmy decide to join Ruiz in this effort, and Jimmy informs Uriel's mother that they are taking him away. They attempt to lift Uriel using a bedsheet, but he proves to be too heavy and falls to the ground. Eventually, they wrap him in a blanket, load him into the truck, and set off to remove him from the area.
During the journey, Jimmy asks their mother if she knows someone who has encountered a possessed one. She responds negatively, and it appears she thinks both of them are merely overreacting. ov Now, they find themselves 300 kilometers away from their village, and Pedro suggests going an additional 100 kilometers.
Ruiz believes they've done the right thing and while having this conversation, Ruiz narrowly avoids hitting a young boy in the road. As they continue for some distance, they stop at a location to leave Uriel, but to their shock, when Ruiz checks the truck, Uriel is no longer inside. They think Uriel couldn't move so he might have fallen from the truck when they swerved.
Pedro suggests that they should go back and look for Uriel, assuming he might be there. However, Ruiz decides it's over and insists that it's no longer their problem. The following morning, Jimena alerts Ruiz that one of their goats has been possessed.
He swiftly goes inside and returns with his gun, intending to finish the goat. Jimena pleads with him not to use a firearm, but he orders her to step back. The goat approaches him, and she places her head in front of the gun's barrel, and Ruiz shoots the goat.
However, Jimena shockingly confronts Ruiz with an axe, resulting in his unfortunate demise, and subsequently, she tragically ends her own life. On that evening, Uriel's brother visits Jimmy and Pedro and informs them that Ruiz and his wife have passed away, and his mother is currently missing. He expresses that they made a mistake by taking Uriel away and asks if he can stay with them, as he doesn't want to go back alone.
Pedro grants him permission to stay in the saddle room, but Jimmy is hesitant about his presence. They take away his revolver and instruct him to depart when the sun rises, emphasizing that he should never return. Before departing, he advises them not to use electric lights, as its shadows call in evil.
The next morning, the brothers decide to leave the town, take their family members, and escape to safety. Jimmy drops Pedro off at his ex-wife Sabrina's house and leaves to meet his family. Pedro requests Sabrina's husband Leonardo to awaken Sabrina and the children and fetch some clothes for him and his brother.
At that moment, Sabrina arrives, clearly surprised to find Pedro unclothed, and urgently urges him to depart. Pedro attempts to clarify the situation and emphasizes his need for clothing. After this he sets his clothes on fire and tries to convince them that they all have to leave because there is rotten in the town.
He thinks he is free and this town will turn into hell quickly. However, Sabrina feels he is lying and he is here to make her feel bad. While they are distracted by the argument, the family dog savagely attacks Leonardo and Sabrina's daughter Vicky.
Santino informs Leonardo that Roger has bitten Vicky, and as he leans down to examine the situation, Roger drags Vicky out of the house. Leonardo and Pedro chase the dog, But when they do not get it even after a long time, they return home. Leonardo begins to head back with his firearm, but Pedro cautions him against using guns, explaining that he might not encounter a dog, but rather a demon.
Pedro then goes to the police and tells them about the dog attack. The inspector tells him that he knows he can't get close to his ex-wife, but Pedro tells him not to shoot the dog and leaves there. However, he hears the gunshot and discovers that Leonardo has indeed shot the dog.
Upon Pedro's return to Sabrina, he is relieved to find that her daughter has returned unharmed. Shockingly, Vicky informs Sabrina that their father will arrive in his car to harm her. Meanwhile, Pedro takes Sabrina's car without her knowledge, and as he departs, he witnesses Leonardo crashing his car into Sabrina.
Pedro continues driving away from the scene, and when Leonardo regains consciousness, he observes Vicky dancing, which adds an eerie and unsettling twist to the situation. After Pedro picks up Jimmy and their mother, the reunited family leaves town. During the journey, Jimmy asks their mother if she knows someone who has encountered a possessed one.
She responds negatively, and it appears she thinks both of them are merely overreacting. Santino asks her to explain what a possessed one is, to which she explains that it's an entity that enters a person's body and utilizes it as a vessel for its own birth. She also tells him that there are seven rules to follow and remember when there is a possessed one, so they don't get into their head and make them do stuff they want to do.
Don't use electric lights, Don't stay close to animals, Don't have to take anything that was close to them, Don't hurt them, and a very important rule, never, ever name the evil by its name, and don't shoot them with firearms. In a surprising turn of events, Sabrina calls on Pedro's mother's phone and expresses her desire to have her children back. Pedro responds that the kids are doing well with him.
Sabrina then claims that their sons don't love him, which is why she cheated on him. She mentions that she knows his location and intends to come and take her children. Pedro, in disbelief, tells her that he witnessed her death and tosses the phone aside, making it clear that the call couldn't have been from Sabrina.
He expresses his uncertainty about the entire situation and the decisions they've made. He admits that he has doubts about their actions, as he brought evil to Sabrina and endangered them all. He believes they should have left the town as soon as they found out about the situation and that he never should have returned to this town.
Jimmy soothes him and says he is proud of him, and cautions him that children are observing and might become frightened. Jimmy guides him to a woman named Mirta, who explains that there's no electricity but there's room for everyone. However, Pedro insists on going to the city.
Jimmy advises him to take a break and rest, and also mentions that Jair needs to clean up. Now they're compelled to stay for a while, and Mirta remarks that the child appears Rotten. Jimmy informs her that he's autistic and inquires if she's ever encountered a genuinely possessed one.
She questions the purpose of their visit, to which he replies that he believes they may have witnessed a genuine possession, though he's uncertain. That night, while everyone sleeps at Mirta's house, Pedro and Jair rest in the car. Sabrina arrives to take Santino with her, and Pedro and Jimmy's mother spot Sabrina, but she's under the influence of sleeping pills.
Sabrina explains that she's come for her children and intends to take them to a place where they'll be safe from harm. After some time, Jimmy approaches Pedro, expressing concern that something is amiss. They rush inside, and their mother explains that she believed she saw Sabrina, but it wasn't her.
Instead, there is someone with Santino. Pedro enters the room and discovers Santino in Sabrina's arms. She explains that she came for her children and then jumps off the balcony.
Pedro rushes downstairs, but Sabrina has disappeared. He then checks on Jair, who is still in the car. Jimmy arrives, and Mirta informs him that the demon is inside Jair.
She asks Jimmy to examine Jair's hands and feet, explaining that a demon has infiltrated his mind. In autistic individuals, they can enter their bodies but struggle to understand their thoughts. They can remain trapped in a limbo for an extended period, eventually leading to possession.
After a while, when Pedro returns home, she tells them that the seventh rule, is dont be afraid of dying. She explains that he cannot go after his son because his fear of losing him empowers the demon, and that evil possess a greater understanding of their fears than they do. She informs them that they must locate the "rotten" individual and eliminate him to prevent the birth of the beast.
Jimmy says the rotten is dead or this wont be happening, but she clarifies that what they're witnessing is the birth process. At the moment, it has only released its essence, and it might not be physically born yet. Therefore, they must finish it to abort the process as quickly as possible.
Before they depart, Mirta warns Jimmy that the town's lights are off. They've cut the power and activated a protocol, so they must exercise caution and avoid using any lights. Jimmy then embarks on a mission to pursue Sabrina, while Mirta and Pedro set out to locate Uriel in their quest to put an end to the demonic outbreak.
Amidst their mission, she tells Pedro that her husband was a shepherd, and they ran a church, but they were frauds. The first possessed individual in Buenos Aires had appeared in their church. Initially, they thought it was an actor they had hired until he vomited over everyone, spewing out the remains of the family he had consumed the previous night.
That's when the Cobras, the monks who taught them how to combat these possessions before they were fully born, came into the picture. For twelve years, they took responsibility for the harm they had caused to people's faith. The ambushes began to multiply, and it's no wonder they killed the cleaner.
This is why everything became shrouded in secrecy. One day, her husband didn't return from a cleaning, and that's when she decided to leave the town. When faced with evil, the only option is to abandon everything and escape to a place even they weren't familiar with.
Pedro asks her why didn't it take her instead of his son? to which she says because he is the one who is afraid. Meanwhile, Jimmy comes across Sabrina walking along the road.
To his shock, he witnesses she has Killed Santino and consuming his brain. Overcome with anger and emotion, he recklessly runs over her, inadvertently colliding with a tree in the process. On the other hand, Pedro tells Mirta that they will have to continue on foot.
Mirta says he must be there at Rural School, because evil likes children and children like evil, and as they proceed, we see Uriel's blanket hanging on a wire. After a while, when Jimmy regains consciousness, he discovers that Sabrina is still alive, and she mentions that he had told her he loved her. Meanwhile, Grandma, who was with Jair in Mirta's house, gets shocked to see Jair walking fine and speaking clearly.
At the school, Pedro questions Mirta about how she knows it's not too late. She responds, Because what evil devours first when it's born is the sound of nature, and the birds and crickets are still chirping. She also tells him no more lights as they cant use electric stuff.
Pedro and Mirta observe some children seated in the classroom. They enter the classroom, but Mirta discovers that they are all possessed, so she swiftly exits and informs Pedro that they won't be able to assist them. She admits that she has never encountered something like this before and is uncertain if she can handle the situation.
At that moment, they notice a boy coming towards them. Pedro approaches the boy and inquires if he knows of somone who's injured or hurt nearby. However, the boy remains silent and quietly proceeds into the school.
This makes Pedro furious, and he tells Mirta that he will make that boy talk no matter how. Mirta says they cant make mistakes as their lives are at stake, and they have to keep an eye on each other. The boy then comes out and asks Pedro if he is searching for Uriel.
He informs Pedro that Uriel is at Teacher Cortez's house, and when Mirta asks if the boy can accompany them, he declines and departs. As Pedro prepares to drive away, Mirta warns him that it might be a trap. Just then, a girl approaches them and reveals that the previous information is false.
She states that Uriel is actually in her house, as her father wanted to help and cure him. She resides in the hills but advises them to be cautious. Pedro gets furious and shoves the girl and starts to attack her.
In the midst of the commotion, Mirta clarifies that Uriel is indeed at this location. They are attempting to divert them elsewhere, it's because they have him here. They discover two lifeless bodies beneath the auditorium stage, and Mirta expresses her shock, mentioning she's never witnessed anything like this before.
Pedro questions if the children are responsible, to which she replies that these individuals are no longer children. She instructs him to go get her stuff and hints that Uriel might be located down there. When Pedro starts tearing up the stage to take out Uriel, Mirta sets up the demon-killing equipment.
Finally, Pedro discovers Uriel hidden beneath a deceased body, and Uriel requests him to end his life. Mirta tells Pedro that the only way to finish him is by using specific equipment and instructs him to bring Uriel out, as she needs to see his nape. As Uriel proves to be quite heavy, Pedro struggles to lift him, and the girl suggests there's an axe in the director's office.
Mirta doubts her, but due to Pedro's growing impatience, he dashes into the office, and Mirta desperately screams for him not to leave her. However, once Pedro realizes it's a trap, the children lock him inside the office, and From there, he watches in horror as the children end Mirta's life and drag her away. After some time, Pedro emerges from the locked office only to find the equipment dismantled.
Fueled by rage, he ends Uriel's life with a piece of broken equipment. However, it's too late to prevent the birth. The demon within Uriel is born, shedding his lifeless body and confronting a defeated Pedro.
The newly born demon taunts Pedro by sparing his life and then walks into the morning sun, followed by the children, as they depart from the scene. Pedro, Jimmy, and Jair return home, and when Jamie goes to saddle room, he finds Uriel's possessed brother who tells him he finished off the original Cleaner four days ago. He also reveals he did the same to his mother the night before and alludes that Jimmy's mother has suffered the same fate.
Inside, Pedro feeds Jair ice cream, but he begins choking and coughs up Pedro's mother's hair and her necklace, having been possessed as well and tricking him under the veil of his autism. Pedro comes outside and collapses in grief, having lost everyone but Jimmy.
