Boo

Jessie is invited by Kevin, Freddy, and Marie to spend Halloween night at the abandoned Santa Mira Hospital. As they arrive, Emmett and his dog Dutchess are briefly attacked by a ghost while preparing scares, signaling that the hospital is truly haunted. Allan, searching for his missing sister Meg, enters with Arlo reluctantly following behind.

Emmett and Dutchess are attacked by a ghost during the setup, forcing them to scramble for safety. The encounter confirms that spirits haunt Santa Mira on Halloween. The danger is just beginning.

While searching for Meg, Allan discovers Dutchess horribly mutilated. The dog suddenly reanimates and attacks him, forcing Allan to defend himself. This grisly encounter foreshadows the hospital's cycle of death and reanimation.

Entering the third floor, Allan finally reunites with Meg, who explains that she got separated from Caitlin. They confront the eerie atmosphere together and brace for worse to come. The reunion confirms Meg's continued presence in the haunted building.

The four friends begin searching for Emmett throughout the hospital. In a private moment, Kevin cheats on Jessie with Marie, revealing tension and fractures within the group. The revelation adds another layer of peril as they press deeper inside.

Jessie, who is spiritually aware, shares the backstory of her late mother who died of disease but still calls to her every Halloween. Her visions hint at Jacob, a child killer tied to the hospital's past. The revelation deepens the sense of impending doom.

The group locates Emmett trembling in the locker room as a terrifying presence lingers. Emmett launches an attack, and Allan and Meg intervene, shooting Emmett to pieces. It is revealed that Emmett and Dutchess have been reanimated.

Paranoia gets the better of Kevin, who shoots Marie dead, suspecting she is turning into a ghost. The group splits up to navigate the hospital's floors: Jessie, Kevin, and Freddy take the elevator with Marie's body, while Allan and Meg take the stairs. Tension and fear drive their choices.

Jessie and Freddy are transported to the third floor, where Jessie has a series of premonitions about Jacob, a child killer who was confined there. Jacob's pattern of murder and attempted escape through fire reveals a malevolent ability to possess the living. The floor becomes a trap as the living try to stay ahead of him.

Jacob's history surfaces: he burned the hospital trying to escape after murdering and reanimating. Nurse Russell discarded the keys, trapping Jacob and his victims inside. Russell's presence deepens the hospital's haunting and her role as a controlling force.

Meg returns with Allan and Arlo, who has already killed the reanimated Caitlin in a bid to save the others. They press on toward escape, only to discover Kevin trapped by a little girl's spirit. The group realizes more of their allies have been turned or endangered.

During the escape attempt, Freddy dies and is reanimated, forcing Arlo to shoot him. The loss underscores the stakes of the night and the hospital's relentless cycle of death and possession.

To break Jacob's hold, Jessie impersonates Nurse Russell and confronts him, intending to scare him from the living world. The ruse succeeds, buying the group a window to flee. Jacob fights back by forcing further reanimations.

Jacob uses Marie's reanimated body to kill Kevin, who is then possessed by Jacob himself. Meg is reanimated and possessed by Russell, yet she retains some control. Russell's possession creates a precarious balance as the group contemplates escape.

Jessie, Allan, and Arlo flee the hospital as All Saints' Day noon approaches. Jacob vows to escape, but Russell warns that he must get through her first before she turns off the lights. The trio exits, aware the nightmare may return once the lights go out.