Siblings Addison (Eric Bana) and Liza (Olivia Wilde) are on the run from a casino heist gone wrong. Their car leaves the road and rolls. A state trooper stops to assist and Addison immediately kills him. Addison tells Liza that they need to split up and cross the Canadian border after which they will meet up. A fierce blizzard is blowing and it seems unlikely they will survive the cold.
Ex-con Jay (Charlie Hunnam) is released from prison and calls his parents, June (Sissy Spacek) and retired sheriff Chet (Kris Kristofferson) to say he'll be home for Thanksgiving. Jay then confronts his former coach who betrayed him when he took a fall during a boxing match and demands his share of the proceeds from the fight. The coach refuses, and Jay, a former boxer, knocks the man down. When he hits his head and is unconscious, Jay believes he's killed him and flees the scene.
Hannah (Kate Mara), a sheriff's deputy, visits Jay's parents and is invited to join their Thanksgiving dinner that night. She returns to the police station and is ridiculed by her father, Sheriff Becker (Treat Williams), who refuses her request to join other deputies in the hunt for the suspects who killed the state trooper.
Staying off the main roads, Jay is driving through the woods when he finds an extremely cold Liza standing in the road. He puts her in his truck and offers her a ride to the nearest gas station. While wandering in the snow, Addison encounters an elderly man tending to his damaged snowmobile. He attacks the man who feigns unconsciousness, then slices off Addison's little finger. The two fight until Addison overpowers the man and stabs him to death. Addison rides off on the man's snowmobile.
Jay and Liza stop at a bar. She sneaks back to his truck to find Jay's parent's address and calls Addison to meet up there. She returns inside and goofs around with Jay by pretending to be a couple to the server. A romantic relationship develops between Jay and Liza as they share their stories. They have sex in a motel. Meanwhile, Addison invades a hunting cabin in the woods and confronts and kills the abusive father. After dumping the man's body, he makes a meal for the distraught wife and her children.
Hannah, gathering information about the killing of the snowmobile rider, receives a radio call relaying a request for the Sheriff's office to check on a woman in a nearby cabin who failed to meet family members as planned.
Liza realizes she has real feelings for Jay and calls Addison. She leaves a message telling Addison that Jay left her, that she couldn't continue with their plan to meet at Jay's parent's home, and that she'll find another ride. When Jay notices Liza has left, he chases her and confesses his feelings for her. To protect jay, Liza says it was only a fling and tries to deflect his romantic interest. Jay persists, and Liza finally confides in Jay that her brother Addison protected her from their abusive father, who was killed when they were young. She tells him she wants to have a family of her own instead of being messed up.
Hannah and two officers snowmobile to the hunting cabin where the missing woman is known to live. When Hannah calls for backup, her fellow officers criticize her and toss her radio into the snow. One of them approaches the cabin. As Hannah retrieves her radio, she sees the frozen corpse of the abusive husband in a stream. She calls out to the officer but Addision hears her screamed warning and shoots the officer with a shotgun through the door, killing him. Addison flees on a snowmobile. Hannah and the other officer pursue him for 10 miles, and during the chase the second officer spills his snowmobile. He forces Hannah off her snowmobile and chases Addison through the woods. He exits the woods onto a frozen lake where Addison is waiting for him and he is garroted by barbed wire Addison left, unmarked, above the trail. Righting the overturned snowmobile, Hannah arrives. She shoots at Addison, apparently wounding him, and calls for back-up. Addison flees, and Hannah is helpless as she watches the second officer bleed out onto the snow and die. Becker arrives and swears at Hannah. telling her she's responsible for the deaths of the two officers because she wasn't supposed to be in the woods.
Addison arrives at Jay's house and holds his parents captive. When Liza and Jay arrive for Thanksgiving dinner, June steps out and tells him about the situation, startling Liza. Addison sees Liza kiss Jay outside, and for a while pretends he doesn't know her. In the sheriffs office, Hannah receives a call from a Detroit detective. She learns that Jay is wanted for questioning about the boxing coach who has a concussion from his fight with Jay. She goes to Jay's parents house to look for Jay and is also taken captive by Addison. At gunpoint, Addison forces them to eat the Thanksgiving meal and to tell what they are grateful for. Liza says she is grateful for a brother who protected her, who killed their abusive father when she was very little, but now she wants that brother to free her. Jay, Hannah, and Jay's parents realize then that Addison and Liza are siblings.
Becker finds Addison's stolen snowmobile near the Mills' house and goes to investigate. He calls for backup before going Inside. He gets behind and shoots Addison in the back, but it turns out to be his daughter, Hannah, wearing Addison's distinctive fringed-leather coat. Hannah seems dazed, but Addison suddenly appears with his shotgun and shoots Becker. Jay attacks Addison and overpowers Addison. He has a choke hold on him when Liza persuades him to stop before he kills Addison. He releases Addison, who shortly recovers, pistol in hand. He demands to know whether Jay loves Liza. Jay replies, and Addison appears ready to shoot Jay when Liza draws her pistol and kills Addison.