In the snowbound peaks of Jotunheimen, a boy with a large birthmark over one eye is hunted through a ferocious blizzard by an unseen pursuer, and the chase ends with him being buried alive in the snow.
Years later, a tight-knit group heads to the same snowy wilderness for a snowboarding getaway. The crew includes Jannicke, Ingrid Bolsø Berdal, her boyfriend Eirik Tomas Alf Larsen, and friends Mikal Endre Martin Midtstigen, and Ingunn Viktoria Winge, plus Morten Tobias. They seek a secluded spot far from crowds and ride the mountain slopes as the light fades. When Morten Tobias suffers a bad fall, Jannicke takes charge of stabilizing his broken leg, but the elements and the distance back to civilization render any rescue unlikely. With no cell reception and the car too far away, they decide to seek help at a nearby lodge they spot on the hill.
Upon arrival, they discover the lodge is deserted. Eirik squeezes through a window to enter, while Jannicke searches for medical supplies and finds a box containing superglue and a single shotgun shell. She uses the alcohol and superglue to stabilize Morten Tobias's injury. The others split up to explore; Eirik, Mikal, and Ingunn locate the lodge’s generator and get the power back on, bringing warmth, music, and abundant food and drink back into the parlor. Meanwhile, Jannicke stays with Morten Tobias, keeping him company as the others wander the halls and rooms.
In the guestbook, Jannicke discovers a chilling note from a previous guest who checked in back in 1975, reading, "We hope you find your son," along with a photograph of a family that includes the boy with the birthmark. The group settles in for the night, while Mikal and Ingunn slip away to a private suite. Jannicke and Eirik share a quiet moment in the parlor, and Morten Tobias sits alone, uneasy but trying to blend in with the celebration.
A disturbing turn comes when Mikal, in the suite, becomes aggressive toward Ingunn, who rebuffs him and sends him away in anger. In the hall, Ingunn hears a strange noise and, thinking Mikal is returning, moves toward the music-filled parlor—only to be ambushed. A figure strikes her with a pickaxe and drags her away, leaving the others oblivious to the danger as the music continues.
The following morning, Eirik heads out to fetch help, only to stumble upon Ingunn’s lifeless body in the snow. He is then struck with the blunt end of a pickaxe and falls. Meanwhile, Mikal returns to Ingunn’s suite to apologize, but the house’s silence heightens the tension. The trio—Jannicke, Mikal, and Morten Tobias—investigate the basement and discover anachronistic objects that belong to a time long after the lodge closed in the 1970s, which raises their nerves.
Jannicke confronts Ingunn’s suite and finds it smeared with blood. A fierce gust of wind and an open door prompt the trio to barricade themselves in a vacant suite, waiting for an intruder to reveal themselves. Footsteps and a pounding door signal that someone—or something—pursues them. As they prepare to run, Mikal escapes through a window, while Jannicke and Morten Tobias struggle to decide what to do about the injured Morten Tobias, who cannot keep up with the others’ plan.
A massive figure—The Mountain Man, cloaked in animal skins and goggles—appears in the lodge, and Mikal is hunted down and killed. Jannicke drags Morten Tobias to a pantry and tells him to memorize the can’s label, hoping it might aid their survival. She narrowly avoids detection as the Mountain Man drags Mikal’s body inside and then searches the building. Jannicke makes a bold move: she steals the shotgun shell and retrieves the keys Eirik had left behind, planning to turn the tables on their pursuer.
In the back room, she finds Eirik alive but bound; she attempts to free him, but the Mountain Man uses Eirik as a human shield, impaling him with his pickaxe. Morten Tobias tries to halt the Mountain Man with a saw, but is unable to do so, and he dies as well. Jannicke, realizing the danger, urges Morten Tobias to run, yet their escape is blocked by the looming predator. She takes a final gamble, grabbing her skis and fleeing into the night, pursued by the Moss-covered hunter.
Buried under a blanket of snow on a sled, Jannicke awakens to find herself surrounded by her dead friends. The Mountain Man carries the bodies to a deep ravine and begins tossing them over one after another. With a last reserve of resolve, Jannicke uses a box cutter recovered from Morten Tobias’s pocket and, as the Mountain Man closes in, she stabs him in the neck. A struggle ensues over a pickaxe, and they tumble toward the ravine. The Mountain Man’s goggles are ripped away, revealing the birthmark over his eye—a cruel echo of the boy from the lodge’s old photo. Seized by surprise, the Mountain Man loosens his guard, and Jannicke seizes the moment to stab him in the stomach with the pickaxe, sending him plunging into the ravine.
A flashback reveals the Mountain Man as a boy, hidden from his parents in the snow, who watch as his parents bury him alive, a haunting origin that explains the chill behind his silent violence. The scene ends with Jannicke, exhausted, collapsing into the snow as the bodies lie around her, and the mountain’s cold winds sweep over the silent, snowbound landscape.
