Jack Russell and Topaz embark on a ski trip to Northern California with their friend Buck Cowan. Also going along are Elaine Marston, a recently widowed friend, and her daughter Buttons. On the slopes, the five enjoy themselves skiing, having snowball fights, and relaxing in the lodge.
The next morning, under the pretense of Jack needing to catch a train back to L.A., Buck drives him to a secluded part of the snowy hills so that when he becomes the Werewolf that night, he'll be miles from other people.
Elsewhere, LAPD Lt. Victor Northrup prepares for his "vacation", loading silver bullets into his revolver. He is heading for Haiti, where his quarry, former werewolf Raymond Coker, consults with the Voodoo priestess, Jeesala.
With a blizzard setting in, Buck returns to the lodge, where he sees several police vehicles. He soon learns Buttons has wandered off in the snow and gotten lost. Rather than joining the search party, Buck takes a snowmobile and speeds toward the point he left Jack.
The moon rises and Jack transforms. Before long he spots Buttons and begins to stalk her. Just as the beast grabs the girl, Buck arrives and tackles him, forcing him to drop Buttons. Buck is no match for the Werewolf who repeatedly slashes him as he tries to protect the girl. He nearly passes out, but as the beast's attention returns to Buttons, Buck makes a last stand, wielding a tree limb. The Werewolf slashes him several more times, and it is all Buck can do to shield Buttons with his own body.
When Buck lies still, the Werewolf runs into the forest. Eventually, the search party find Buttons and Buck, who may be dead.
Morning comes, and the again-human Jack trudges through the fresh snow, to seek out his stashed clothes.