Twelve-year-old Cole Johnson is bullied by his neighbor Jeremy, but his babysitter Bee stands up for him and scares Jeremy off. The following day, when his parents go out for an overnight stay at a hotel, Bee and Cole spend quality time together until he has to go to bed. Cole is encouraged by a text from his neighbor and best friend Melanie to go see what Bee gets up to after he goes to sleep. To his surprise, he sees what looks like Bee and several of her high school friends: Max, John, Allison, Sonya, and Samuel. They are playing a game of truth or dare formatted as a game of spin the bottle. However, as Bee kisses Samuel on a dare, she pulls two daggers from behind her back and stabs him in the skull. The others collect Samuel's blood, revealing themselves to be members of a demonic cult. Cole hurries to his room where he calls 911, puts on his shoes, and finds a pocket knife. He pretends to be asleep as Bee and the cult members enter his room to draw a blood sample. After they leave, he tries to escape out the window but Bee stays in the room, and Cole passes out from the exhaustion.Bee and her cult question Cole, while fending off his questions by saying it was a science project. When the cops arrive, Max kills one with a poker, but the cop accidentally shoots Allison in her breast, whereas Bee and Max kill the other cop. Bee forces Cole to give them the police code to call off the other cops. While Allison complains about being shot, Cole rushes up the stairs; John pursues him, but is pushed over the banister, landing on a trophy that impales his neck.Cole escapes out his bedroom window and hides in the crawlspace under his house. Although Sonya finds him, he traps her in the basement and then ignites a firework rocket and bug spray to blow her up. After showing appreciation for Cole's ingenuity, Max chases Cole up the old tree house; he is killed when he falls and is hanged by the rope swing. Cole escapes to Melanie's house, but Bee follows him. While hiding in a room, Cole apologizes to Melanie for dragging her into this situation and assures her that he is going to take care of things. He asks Melanie to call the police, then she kisses Cole before he leaves.Cole returns to his house to find Allison, who tries to kill Cole with a kitchen knife; she is instead shot in the head with a shotgun by Bee. Bee explains to Cole that when she was young, she made a deal with The Devil to get whatever she wanted by sacrificing innocent people and spilling their blood on the ancient book while reciting its verses. Although she wants him to join her cause, Cole refuses and burns the spell book. He rushes to Melanie's house to take her dad's car, and drives it straight towards his house while Bee fixes the book in the living room. After crashing into her, they have one last emotional farewell before Cole climbs out of the wreckage. As the police and emergency crew arrive, Cole tells his parents that he no longer needs a babysitter. Later, a firefighter going through Cole's house is attacked by Bee.