In 1984, the Briseño family, atheists seeking a fresh start, leaves the United States for Durango, Mexico and moves into a looming manor that locals say is haunted after the mysterious deaths of its previous occupants. The youngest daughter, Karem, hears muffled whispers from the basement but finds only a single toy left behind. The next day, she faces bullying at school for being the new girl and for her atheistic views. Isolated in her room, she keeps a diary and reaches out to an invisible presence who presents himself as [Naro]. He seems to know intimate details about her tormentors, offers his aid, and grants her a peculiar telekinetic ability.
As the power grows, Karem’s shy, restrained nature shifts into something explosive, drawing the attention of her teacher, Clarissa, who subsequently grounds her after a loud classroom outburst. The Briseños are visited by Father Miguel, a priest who senses something off about the family and recalls a past tragedy tied to the manor. His investigation hints that [Naro] is a fearsome demon who once granted abilities to a family’s youngest son and provoked a catastrophic unraveling when confronted by relatives who refused to believe the danger.
The crisis intensifies when one of Karem’s bullies, Fabiola, falls ill and regurgitates blood with a cryptic note, prompting Elizabeth and Adriana to confront Karem. In response, the girl unleashes her powers and kills the two classmates, injuring Clarissa in the process as the school mourns and goes on lockdown. With Clarissa in intensive care, Karem and her sister Laura attempt to take her to the hospital under the pretense of visiting her, but the situation spirals: Laura becomes possessed by Karem, manipulating her to smother Clarissa to death in the hospital.
Driven by guilt and fear, Karem confronts Naro, only to have the demon seize control of both her and her brother’s bodies. As the two brothers are drawn toward the manor, Father Miguel finds Abraham and Mariana and pleads for help. Inside the manor, spectral phenomena escalate—poltergeists, and Naro materializes as a charred boy. Mariana reaches out to the girl, who is now fully under Naro’s control, and murders her mother. A cardinal, along with several priests, arrives to exorcise the haunting, while a possessed Eduardo fights against them with demonic force. The cardinal’s exorcism eventually expels Naro from Mariana’s corpse, but not before tragedy strikes again, as Naro overcomes the ritual and drives the demon into a final assault on the priest and Miguel, killing them both when the process tears away the cardinal’s arms in front of Abraham.
With only the cardinal left alive in the manor, [Karem] makes a desperate assault during the exorcism and stabs him in the stomach. The church covers up the events, takes Karem into custody, and seals her diary in a vault, leaving the Briseño saga to be hidden from the world.
Sometime later, [Laura] is contacted in her cell by Naro, and she smiles as she reads his message. In a mid-credits scene, Karem is escorted by a nun to a room where she is lobotomized to dull her abilities and sever her link to Naro. After the credits, the final photograph of the real Briseño family appears, accompanied by a Latin phrase that supposedly echoes the words the possessed Karem used: “Quia non refert quid vis ut nunc. nonne tu es hinc. Hinc illum sicut me,” a haunting reflection of the demon’s hold.
> Quia non refert quid vis ut nunc. nonne tu es hinc. Hinc illum sicut me
