In 1974, at the Glensville Sanatorium, West Virginia, Dr. Brendan Ryan (Arne MacPherson) shows local psychiatrist named Dr. Ann McQuaid (Kristen Harris) around the psychiatric hospital. He shows his three deformed patients, Three-Finger, One-Eye and Saw-Tooth, who all have the ability to sustain injury and not feel it. While Dr. Ryan and Dr. McQuaid move on, one of the mental patients grabs Dr. McQuaid's hair and rips out her hair clip, which she does not notice. The patient gives the hair clip to Saw-Tooth. The three deformed patients use the clip to pick the lock and escape from their cells. They release the other patients and together they kill the orderlies and the doctors, including McQuaid and Ryan.
Twenty-nine years later, nine Weston University students - Kenia (Jennifer Pudavick), Jenna (Terra Vnesa), Vincent (Sean Skene), Bridget (Kaitlyn Wong), Sara (Tenika Davis), Claire (Samantha Kendrick), Kyle (Victor Zinck, Jr.), Daniel (Dean Armstrong) and Lauren (Ali Tataryn)- are snowmobiling, on their way to their friend Porter's cabin in the mountains. However, they get lost in a snowstorm and are forced to take shelter in the Glensville Sanatorium, where the surviving cannibals (Three-Finger, Saw-Tooth and One-Eye) settled. The teens explore the asylum and decide to wait out the storm. Lauren remembers her brother's stories about the sanatorium and the cannibals, but her friends do not believe her. After the group go to bed, Vincent, suffering from insomnia, begins strolling around the asylum. After he finds Porter's corpse, he is murdered by Saw-Tooth before he can alert the others. The next day, as the storm continues, the teens notice that Vincent is missing and begin to look for him. While searching for him, Jenna witnesses the cannibals butchering Porter's body, and she runs back to warn the others. After they find Porter's severed head, Claire is caught around the throat with a strip of barbed wire and lifted up to a nearby balcony. Kyle attempts to save her, but the cannibals pull the wire tighter, decapitating Claire. The group flees, but the cannibals have stripped off the spark-plug wires on their snowmobiles. Lauren skis down the mountain to seek help, while the others barricade themselves in a doctor's office.
Later, Sara, Daniel and Kyle go to the basement to find weapons. After discovering an arsenal of knives and other tools, they return to the others, but the cannibals capture Daniel. The rest of the group overhear his screams and runs back to save him, but they arrive too late and Kyle finds the cannibals eating Daniel alive. The teens chase the cannibals, successfully trapping them in a cell. They begin to kill them but Kenia refuses, saying that they will be just like the cannibals if they resort to execution now that they have them at bay. The girls leave Kyle to guard the cannibals as they set off to find the spark-plug wires. While Kyle is asleep, the cannibals use Dr. McQuaid's hair clip to escape and attack him. Giving up their search for the spark-plug wires, the girls return to the doctor's office. During the night they mistake Kyle for a cannibal and accidentally stab him to death.
Realizing that they are locked in the building, Sara breaks a window and digs a tunnel through the snow. The girls escape, but Jenna is killed before she can get out. As Kenia, Sara and Bridget attempt to get away, the cannibals chase them on snowmobiles. The girls are separated and the cannibals attack and kill Bridget.
As the day dawns, Lauren has frozen to death in the storm. Kenia is still searching for the road when One-Eye reappears on a snowmobile. Sara arrives and saves Kenia, knocking One-Eye off the snowmobile and allowing the pair to steal it. As Kenia and Sara drive away, they accidentally run into a strip of barbed wire and are decapitated, a trap set by Three-Finger. Three-Finger picks up their heads and puts them in a tow truck, before driving away with the other cannibals.