Chyna Shepherd, Molly Parker, accompanies her friend Laura Templeton, Deanna Milligan, to her family's house in rural Washington State for Thanksgiving dinner. A serial killer named Edgler Foreman Vess, John C. McGinley, invades the home and kills Laura and her relatives while Chyna hides in the killer's RV. When Vess stops for gas, Chyna makes her escape and pleads with two attendants to call the police. Before she has a chance to explain, Vess returns and torments the workers before brutally killing them with a shotgun.
Chyna soon learns that Vess is holding a 14-year-old girl named Ariel hostage in a fortified basement room. She becomes determined to save Ariel and steals one of the shopkeepers’ cars to follow Vess back to his home. On the highway, she encounters a woman named Miriam Braynard, Piper Laurie, and asks for help calling the police. Miriam stops at a gas station and discovers the shopkeepers’ bodies, which leads her to believe Chyna’s story. She makes a frantic phone call to the authorities, telling them that they need to save Chyna and Ariel, which the police initially dismiss.
Meanwhile, a policeman, Ethan Trevaine, Blu Mankuma, begins piecing together the missing-person clue and starts to investigate. Chyna’s car runs out of gas and she abandons it in the middle of the road, forcing Vess to stop. As he pushes the car down an embankment, Chyna slips into his RV and hides, unknowingly leaving footprints. Vess senses another intruder but feigns innocence. He fatally kills Miriam when she tries to intervene to help Chyna.
When they reach Vess’s home, Chyna again attempts to free Ariel but is overpowered and restrained. In captivity, she experiences flashbacks to a traumatic childhood: as a little girl, she witnessed her disturbed, abusive mother and her boyfriend kill their neighbors. In turn, Vess reveals his obsession with the “intensity” of experience and his intention to kill both Chyna and Ariel, offering a slightly more merciful death if she agrees to help him torment Ariel out of her catatonia. The two share intense conversations about God and the nature of good and evil.
As Thanksgiving ends, Vess is late returning to work and lies about a last-minute trip to Portland. He departs, leaving Chyna chained to the dining room table. She watches in horror as one of Vess’s other captives escapes through a drain hatch in the backyard, only to be mauled to death by his savage German Shepherds. Seizing the chance, Chyna frees herself and escapes with Ariel. She disguises herself in Vess’s dog-training gear and uses ammonia to blind the dogs, but a triggered alarm forces them to abort their escape and Vess returns home early.
An unmarked vehicle and a police car appear. Although Chyna believes Vess is inside the unmarked car driven by Trevaine, it turns out that Vess is the sheriff who emerges from the police car and shoots Trevaine. Chyna and Ariel manage to hide and then make a renewed assault on their pursuer, returning to Vess’s house. There, Chyna gains the upper hand, sets Vess on fire, and confines him in Ariel’s old room, watching as he burns to death.
In the aftermath, Chyna visits Ariel in a psychiatric hospital but is denied custody; the social workers explain that Ariel will need extensive therapy to recover from the trauma. As Chyna prepares to leave, Ariel, for the first time, speaks and calls out the name “Badger,” a character from a story Chyna had told to give Ariel courage while escaping from Vess. The two share a quiet, hopeful embrace, and it is implied that Chyna’s custody of Ariel was granted.
