On a sun-soaked vacation, a group of college students bands together for a beach party before retreating to a remote cabin. The crew includes Nick, his younger sister Erin, and their engaged friends Vicky and Josh, along with Tera. After night falls, a masked intruder named Edgar, acting on orders from his boss Wayne, crashes the gathering. Nick, who had been locked outside, witnesses Edgar strike Erin and manages to free Tera before falling to tranquilizers himself. Tera darts for a boat but is quickly caught, and Vicky and Josh are knocked unconscious, setting a brutal chain of events in motion.
When Nick, Erin, and Vicky awaken, they find themselves chained inside a feed-lot barn. Josh is separated and gagged in a separate stall. Wayne, the barn’s hard-bitten owner, declares that they are now his property and that he intends to break them, “like horses.” Josh’s defiance earns him a brutal consequence as Wayne and Edgar cut out his tongue. Edgar then takes Vicky away, raping her with Wayne’s permission, while Kathy—a longer-held prisoner who later reveals herself to be deranged—presents a looming threat to Erin, singing a macabre nursery rhyme that unsettles everyone. Nick is forced to endure an overnight stint in the shed, a plan to erode his spirit, and he glimpses a disturbing sight: Tera’s body wrapped in plastic.
The situation escalates when Amell arrives in a car to inspect the captives and agrees to buy Vicky, leaving Wayne disappointed that he didn’t deliver more. Vicky is sealed in a box and sold, while Wayne coldly shoots Josh when his incoherent protests become too loud. A couple stops to ask for directions, and their daughter wanders into the barn; Edgar murders them with a knife and Edgar then pursues Nick, who manages to free himself and strike back with a crowbar, killing Edgar and injuring Wayne in the process. Erin and Kathy are freed as Wayne is locked into a stall, and the trio flees in Edgar’s truck.
As they drive, Kathy urges them to take a left toward lit buildings, but she slips away to pursue cigarettes. Erin is soon attacked and killed by Wayne, and Nick discovers Liz, a young woman Liz locked inside a box. He realizes Kathy’s deception and hides in the box himself, waiting for the right moment to act. When Kathy checks on “Liz,” Nick emerges to shoot Kathy and frees Liz, then lends Liz Kathy’s gun and heads off to find Erin. Wayne intercepts and shoots Nick with buckshot, but Liz holds him at gunpoint while unable to pull the trigger; the distraction allows Nick to cripple and finally kill Wayne with a circular saw.
Wounded and reeling, Nick tells Liz that everything will be all right, but Kathy reappears and fires, shooting both of them. In the haunting final image, Kathy is shown purchasing another remote barn, signaling that the nightmare could start anew.
