Winter 1977. The Rill Lodge and Ski Resort in Colorado is holding its 50th Annual Winter Carnival and is expecting a record turnout. Unbeknownst to the assembled people, however, something is lurking in the woods, not quite human and not quite animal. Two friends skiing on the North slope, Heidi (Annie McEnroe) and Jennifer (Kathy Christopher), find mysterious tracks and hear some disturbing noises coming from the woods. Heidi takes off, but Jennifer lags behind and is set upon by a monstrous beast.
Tony Rill (Robert Logan), manager of the resort, is summoned and told that a female skier was found, babbling incoherently about some sort of monster and her missing friend. Rill, doubtful at first, listens to Heidi's story and, despite being unsettled by what he hears, surmises that it was probably a grizzly bear. He and a search party set out and split up to find Jennifer. Rill comes upon a remote stretch where he finds Jennifer's jacket, bloody and torn to shreds. He also hears a monstrous roar come from the woods and turns just in time to glimpse something white, hairy and massive at the edge of the treeline.
Meanwhile, back at the resort, Gar Seberg (Bo Svenson) and his wife Ellen (Yvette Mimieux) arrive. Seberg, a former Olympic Ski champion, has fallen on hard times and has come to Colorado to see if his old friend Rill can give him a job. As they step into the main building, Seberg gets the brushoff from a worried Rill, and begins to feel that this whole thing was a bad idea. Rill, meanwhile, informs his grandmother, and owner of the resort, Carrie Rill (Sylvia Sidney) about what he saw and heard, and tells her that they should put up signs restricting access to the area and inform the sheriff. Carie, however, is put off by the thought of a story about some wild man-beast roaming the slopes hurting business, and convinces Rill that while no one will believe Heidi, his word is another matter altogether. She agrees that he should merely post signs around the slopes warning of possible avalanches, arguing that no one has actually *seen* the creature, nor has it ever come down from the slopes. No need to worry everyone needlessly and bring the sheriff in on the mater, concluding that, despite the possibility that Jennifer suffered a horrible death, "I'm not being insensitive, just realistic". Rill is reluctant, but decides to go along with his grandmother's plan.
Stepping out of the office, Rill apologizes to Seberg and Ellen for the cold shoulder, explaining that there was a serious issue he had to attend to. With the apologies and handshakes out of the way (and some flirtatious banter between Rill and Ellen), Seberg tells Rill he needs a job, and is delighted when Rill happily hires him. Rill, meanwhile, returns to the slopes and tells one of his men, Buster Smith (Thomas Babson) that he and the others are to post signs saying "Restricted Area" and put them along the edge of the slope where Jennifer's jacket was found. Smith, unsure as to why his boss is so spooked, argues that he thinks he knows where Jennifer might be and requests to take a searching party to look for her. Despite RIll's emphatic "no", Smith takes off and heads out to the remoteness of the North Slope. A misstep on his part sends him scrambling down the slope, where he comes face-to-face with the monstrous Snowbeast. His screams echo through the woods.
Ben Cochran (Richard Jamison), maintenance director for the lodge, and his son John (Jaime Jamison) show up with some workers at the Fairchild Farm, an abandoned barn that Heidi indicated she and Jennifer had skied past. John runs inside the barn, but quickly steps back outside, shaken. His father runs into the barn, where he finds the mutilated remains of Jennifer. Out in the woods, monstrous eyes survey the barn.
Rill and Seberg pull up to the lodge, where they find Sheriff Cole Paraday (Clint Walker). Before Rill can talk to him about the strange goings-on, Paraday gets a message over his radio about a possible murder at the Fairchild Farm. He takes off, leaving a confused Rill and Seberg wondering what happened to set the sheriff off in such a hurry.
Rill, meanwhile, returns to the lodge to find Seberg surrounded by adoring fans and Ellen off to the side, sitting alone in the dining hall. They begin to talk, and we learn that Rill and Ellen were once lovers, and that, instead of marrying Rill, she married his best friend, Gar Seberg, a decision which she is now beginning to regret. Ellen strongly suggests that she wants to have an affair with Rill, but Rill resists her advances, for now. As Ellen leaves, Seberg walks in and Rill asks him if he can confide in him about something important. Seberg, intrigued, balks when Rill insists that Ellen must be kept out of the loop because she is a television reporter, but before they can converse further, Carrie, panicked, stops Rill. He tells Seberg to meet him in an hour by the pool.
At the Fairchild farm, Paraday and his deputy are shaken by what little John Cochran found, and Paraday sends his deputy off to find Rill. Meanwhile, at the pool, Rill tells Seberg what he has seen and theorizes that it is some sort of Bigfoot creature that is terrorizing the resort. Seberg recalls that Ellen once did a special on Bigfoot. Rill asks Seberg if he is still an expert marksman. Seberg replies that he is still pretty good on the rifle range, but Rill points out that this is going to be a moving target. Seberg is horrified at what Rill is suggesting, and accuses his old friend of giving him a job in order to make him a hired gun. Rill argues that he is only doing this for the good of the town and its people, as Seberg points out that Rill doesn't have the right to order the death of something that may be part-human, and that every report about Bigfoot has pegged the creature as docile. Rill reveals to Seberg that he found Jennifer's jacket, bloody and destroyed, and believes that whatever killed her is too dangerous to simply ignore.
Back at the lodge, Ellen, all bundled up in a snow bunny outfit, is dismayed to learn that both Rill and her husband have seemingly disappeared, and is even more disturbed when the deputy pulls up and tells her and Carrie that Rill needs to get out to the Fairchild Farm ASAP. Ellen straps on some skis and decides to go go the farm. She arrives at the farm, but Rill and Seberg are nowhere to be found. She *dos* find some mysterious-looking tracks, and decides to follow them into the woods.
Rill and Seberg finally arrive at the farm, and they walk into the barn. Rill offers to look at Jenifer's face to identify her, but is informed by the sheriff that her face was completely torn off. Rill is chilled by the statement but is able to identify Jennifer through her torn outfit, which matches her jacket. Rill informs Paraday that he and Seberg think that a Bigfoot killed Jennifer. The sheriff, somewhat skeptical, nonetheless listens to their theory. Still not convinced that it *was* a Bigfoot, the sheriff decides that whatever killed Jennifer is too dangerous to be allowed free reign of the woods, and that the three of them should go out the following morning, track it down, and kill it. Seberg, despite his previous aversion to killing the creature, concedes that the Snowbeast is much too dangerous and bloodthirsty to leave alive.
Ellen, meanwhile, continues to follow the tracks into the woods. She quickly realizes that she has gotten lost. As the sun is slowly setting behind the mountains as nightfall approaches, she hears an ungodly roar come from the woods....
Nighttime. The lodge is bustling with the activity of the Winter Carnival, as girls go scurrying around getting their dresses ready and the band practices for the ceremony. As Carrie puts the finishing touches on Snow Queen Betty Jo Blodgett (Jacquie Botts), the women are horrified to glimpse a monstrous face in the window. The Snowbeast breaks the window and panic ensues as everyone storms out of the room into the main hall. Outside, Betty Jo's mom (Liz Jury), oblivious of the goings-on, pulls up in her 4x4, only to be confronted by the horrifying Snowbeast. Betty Jo runs outside and opens the door to her mother's car, only to find the torn and mutilated remains of what was once Mrs. Blodgett.
Inside the lodge, chaos ensues and Seberg, realizing that something is amiss, goes off in search of Carrie. She tells him that there is a monster outside and promptly gets knocked down and stomped on by the frenzied crowd. Shortly thereafter, the scene calms down and the police are left scratching their heads as to how to explain the carnage in Mrs. Blodgett's car. Carrie begs Seberg to apologize to Rill, stating that Rill was right all along and that she should have put the sheriff in the loop from day one. Seberg returns to his room, and realizes that in, the ensuing chaos, Ellen is nowhere to be found. Surmising that she must have set out earlier to find he and Rill, he straps on a pair of skis, the first time he has done so since his Gold Medal performance 9 years earlier at the 1968 Olympics, and sets off to find Ellen in the pitch-black wilderness.
At the Fairchild Farm, Ellen has been able to sneak in and sleeps uneasily. Suddenly, she hears the barn door creak open and something heavy moving through the barn. Preparing for the worst, she is overjoyed to find her husband walking through the barn. They embrace and begin to prepare for the long night. As they build a fire, Seberg states that he's surprised that after 9 years he was able to take to his skis again like a fish to water. He then opens up to his wife, telling her that he knew she always questioned his decision to leave the sport altogether after the '68 Olympics, and that he did it because he didn't want to become some has-been hanging onto past glories. As Seberg tearily confesses that his retirement only made him miserable, Ellen gains some newfound respect and love for her husband.
Morning. Seberg and Ellen wake up and begin preparing to head back to the lodge. As they walk by a loft, Ellen bumps into a ladder and body pieces begin to rain down. Realizing that they have stumbled onto the monster's feeding lair, they scramble out, but are stopped by the Snowbeast as it tries to return to the barn. They appear to be hopelessly trapped, but just at that moment Paraday, his deputy and Rill arrive on ski-mobiles, looking for the creature. Furious at the intrusion, the Snowbeast races off into the woods. As Paraday and his deputy take off after it, Seberg and Ellen are reunited with Rill and they return to the lodge.
A view of the once-bustling resort now reveals every businessman's nightmare: Ski-lifts shut down. Empty parking lots and cabins. The resort has become a virtual ghost-town. Rill, Seberg and Ellen prepare to set off in pursuit of the monster, but suddenly the deputy bursts into the lodge and informs all the assembled that he and Paraday have captured and killed the creature. As everyone rushes outside, the trio are dismayed to find that the two lawmen have instead killed a large grizzly bear.
Seberg and Ellen confront the sheriff and accuse him of giving up the hunt for the monster. Paraday tries to convince them that there is no scientific proof to back up their claims that it was a Bigfoot that killed Jennifer and Smith, but Seberg retorts that deep down the sheriff knows that if they cut open the grizzly they won't find any human remains in its stomach. Defeated, Paraday asks them what they want to do. Their solution is the only rational one: Get together with Rill, and set off to finally confront and kill the creature. Meanwhile, a funeral is held for Buster Smith, whose remains were the ones found by Ellen and Seberg in the barn.
The following morning, Rill, Seberg, Ellen and Paraday set off in a camper in search of the Snowbeast. They set up camp on a deserted stretch of road and go into the woods in pursuit of the creature. Hours later, they have found nothing and in the process have exhausted themselves. Returning to the camper, they find that something has torn off their skis from the back of the camper. Deciding that it would be fruitless to go off after the creature, as well as putting themselves at a disadvantage by confronting it in its element, the party decides that now that the monster knows where they are, they will let *it* come to *them*, and set up a watch-detail in groups of two. Ellen suggests that her husband and Paraday take the first watch while she prepares dinner. Inside the camper, she and Rill finally confront their mutual feelings for each other, and decide that the best course of action would be to remain friends and nothing more. Shortly thereafter they relieve Seberg and Paraday.
The following morning, the party finds nothing amiss. However, the creature is spying on them and kicks a stack of piled-up firewood down an embankment at the camper. Seberg, Ellen and Rill escape and climb up another embankment to avoid the rolling logs, but Paraday gets trapped in the camper. The trio can only watch and listen in horror as the Snowbeast kills Paraday. They return to the camper, only to find the monster's tracks and a pool of blood where Paraday had been trapped. Ellen climbs into the overturned camper to get a rifle while Rill climbs into the cab to retrieve Paraday's revolver. Suddenly, the monster appears on the embankment overlooking the toppled camper. Rill fires off a shot and hits it, sending it screeching back into the woods. Knowing that Rill has only wounded it, and that a wounded creature is doubly dangerous, Seberg straps on his skis, takes the revolver and sets off after the Snowbeast for the final confrontation...