Paranormal investigators Ed and Lorraine Warren bring the haunted doll Annabelle to their locked artifacts room, hoping to confine its malevolent influence. Their daughter, Judy, becomes the unwitting target of supernatural attention when her babysitter, Mary Ellen, is left in charge for the night. Mary Ellen’s curious friend Daniela, seeking answers about her deceased father, visits the house and explores the artifact room, inadvertently unleashing Annabelle’s evil. The doll's presence awakens other malevolent spirits within the room, leading to a night of escalating terror and supernatural chaos that targets everyone in the house.

As spirits and entities wreak havoc, Judy, Mary Ellen, and Daniela must find a way to contain the unleashed horrors and restore order. They rely on their wits and courage to survive the night, with Judy drawing on the lessons learned from her parents' work. The tension rises as the three girls confront the increasingly dangerous spirits, pushing them to face their deepest fears. The battle between good and evil intensifies, leaving them to navigate a surreal nightmare where reality and the paranormal blur.