After a woman uses heroin and dies by suicide, a documentary-like montage unfolds, tracing the troubled history of Exeter School of the Feeble Minded. The institution’s grim past is laid bare through clips that reveal years of abuse toward its patients, its slow decline, and ultimately its abandonment. Years later, Patrick volunteers to help Father Conway renovate the derelict site. Conway, who feels Patrick has squandered opportunities by not pursuing college, believes that God has a special plan for him. After a brief discussion with Greer, a local junk man, Conway and Patrick decide to leave for a weekend away from the bustle of town.
Back at Exeter, Patrick and his friends discover that the site will be unsupervised for the weekend. Seizing the chance for a big party, they proceed despite Patrick’s objections. As the party winds down, seven people remain: Patrick, his younger brother Rory, Brian, Brad, Amber, Drew, and Reign, a girl Patrick had met that night. The group contemplates the site’s troubled history and wonders whether it still harbors supernatural phenomena. Amber, convinced there might be something more to the place, persuades the others to try a levitation of Rory. She claims it worked before, but the others dismiss it as a prank by Rory, who they accuse of seeking attention. Embarrassed after wetting himself, Rory runs off into the shadows of the old building.
Later, when Patrick and Reign encounter Rory again, they become convinced he is possessed. He speaks in tongues and attacks anyone who approaches him. After restraining him, Reign urges Patrick to call Father Conway for help. The others react with anger and fear, having consumed a slew of illegal drugs throughout the night. The tension spikes when Greer returns and, attempting to coerce Amber into sex to avoid trouble, threatens violence. Greer is drawn upstairs by a strange sound and is killed by Rory. The ensuing panic prompts Brian and Amber to flee Exeter, but their escape is abrupt and tragic: they crash into the car that is meant to carry them away, striking Father Conway and effectively ending his life at the moment the car fails to break free from the grounds.
With two dead bodies and a stash of drugs left behind, the teens realize they are trapped as the security system locks them inside. Faced with a growing crisis and a mounting sense of danger, they decide to handle the situation themselves. They search for help on their cell phones and find a do-it-yourself exorcism guide, attempting to perform it on Rory. At first, the ritual seems to work, and Rory calms, but the peace is short-lived; he soon reverts to a possessed state. Seeking clues, Reign and Patrick uncover video footage of another troubled teen from Exeter, Devon, who appears to be Conway’s child. A chilling message written in blood on a ceiling demands that the group address the entity, so they carve out a makeshift Ouija board.
The entity identifies itself as Devon and claims it is trapped in a box, asking the teens to help free it. Rory initially recovers from possession but does not remember what happened. Amber then begins showing signs of possession herself, and she brutally kills Drew before the others drive her away from the building. Brad, frustrated and terrified, arms himself with a pickaxe and hunts Amber, only to encounter Father Conway in the confusion. He trips and is fatally stabbed by the tool, a mistake that seals his fate and adds another layer of chaos to the night. Reign and Patrick pursue Amber while Rory and Brian guard the downstairs corridor.
Amber is killed, and Rory explains that Conway had trapped him in a box “for his own protection.” The group discovers Brian, who is now possessed; Patrick kills Brian to prevent further harm. Reign insists that Conway is behind the events and accuses him of summoning evil spirits. Rory, also skeptical of Conway’s motives, agrees that something is deeply wrong. Patrick remains convinced that Conway would never hurt anyone, but they eventually locate the security system, disable the lockdown, and Patrick forces Rory to flee to safety.
The confrontation reaches a fever pitch when Conway murders Reign, and Patrick, furious, accuses him directly. Conway denies having a son, and in a final act of rage, Patrick sets him on fire, ending Conway’s life. In a startling revelation, Reign rises and discloses that she is Conway’s daughter, Devon. Devon explains that Conway abandoned her and her mother, and after Devon’s mother committed suicide, Conway hid Devon at Exeter. Fueled by abandonment and a desire for revenge, Devon engineered the whole sequence so that Patrick would kill Conway. In the climactic struggle, Patrick traps Devon in a box as Exeter burns around them. The film closes with two cops arriving to investigate the ruins, only to find the box empty, leaving Devon’s fate—and the true extent of Conway’s malice—ambiguous and unresolved.
Across the escalating horror, the film maintains a somber, restrained tone, emphasizing the consequences of neglect, secrecy, and cruelty within a place meant to heal. The unsettled atmosphere of Exeter lingers long after the flames die down, inviting viewers to ponder what truly lingers in abandoned spaces and how past sins can resurface in the most unexpected, devastating ways.
