In an unspecified snowy wilderness, a group of loggers are finishing work for the day and prepping a massive roast when a grotesque axe-wielding man emerges from the woods, massacres nearly everyone, then runs the foreman through the circular saw. Sometime later, a group of five young first-time offenders, Marty, Trish, Zack, Rosa, and CB, are taken into the woods for a week long rehabilitation excursion led by Sergeant A. Hoke and Ms. Sam Kowowzinkowski, a guidance counselor. When they arrive at the remote cabin, Hoke tells the others they will all be sleeping in tents outside while he enjoys the cabin. In the nearby woods, a grizzly bear is stalking a deer when a giant man (Bunyan) emerges from the trees, picks up the grizzly, snaps its neck, then skins and cleans the carcass.
During a night around the campfire where Ms. K talks with the youths, a local hermit, Meeks, crashes their program discussion, startling them, before Hoke runs him off and sends everyone to bed. The following morning, Hoke takes the others on a grueling hike. When they stop for lunch, Zack and Martin find the bones of a large ox jutting up from the ground. Zack takes a horn from the skull as a souvenir. Later, Bunyan visits the site, revealing it to be the grave of his ox, Babe, and finds the skull missing a horn, which enrages the giant.
The delinquents, Hoke and Ms. K stop for a break in their hike. When Martin and Zack toss the horn back and forth, a wind passes through it, alerting Bunyan to their location. The giant emerges from the trees behind an oblivious Trish—who’s distracted when her phone picks up a rare signal—and brings his axe down on her, splitting her vertically in half. The others run away in a panic and Bunyan bisects Hoke, but lodges his axe in a tree, which allows the others to escape back to the cabin. Bunyan follows them and pulls their van away with him, trapping them, then returns to his cave.
Meeks runs into the campgrounds in a panic and the others let him in the cabin. Once he sees the horn, he tells the group of their misdoing and that the tall tale of Paul Bunyan is based on an actual person, the son of a 19th century lumber baron and European immigrant. He was born with a rare condition that caused extreme gigantism as well as tripling his life expectancy. In adolescence, Bunyan’s blue ox, Babe, got wounded and wandered into some loggers’ area, who in turn killed Babe for the meat. Bunyan slaughtered the loggers in retaliation, which caused the nearby townspeople to seal him inside an abandoned mine. Bunyan survived and grew to his full height while living in the mountains. Meeks tells them they must return Babe’s horn to Bunyan’s shrine or they will all be killed.
Upon hearing this, Zack runs out of the cabin with the horn and throws it into the forrest. The horn is thrown back out of the trees and impales Zack; Bunyan emerges, drags Zack’s body off and returns to his cave to sharpen his axe. CB’s father (who’s also the local sheriff) is called to the area for a bear sighting but finds Hoke’s body. Bunyan returns and smashes through the roof of the cabin. He grabs Rosa and throws her against a tree, killing her. The others rush outside and as Bunyan is about to attack them, he’s shot with several tranquilizer darts by CB’s father, who’s just arrived on the scene. Bunyan falls backwards incapacitated, and crushes the cabin. Meeks emerges from the woods and hold them all at gunpoint while defending Bunyan. He shoots Martin and prepares to kill the others, but Bunyan regains consciousness and decapitates Meeks. Bunyan chases Sheriff, CB, and Ms. K to a footbridge over a river where they are trapped until a militia composed of local hunters arrives. They empty their weapons into Bunyan who falls seemingly mortally wounded into the river below and sinks. Sheriff, CB, and Ms. K leave with the militia.