During Christmas vacation at the rural Calvin Finishing School For Girls, a student is killed when she is accidentally pushed over a balcony during a prank. Two years later, on the Friday before Christmas, five students — Nancy [Jennifer Runyon], Melody [Linda Gentile], Leia [Judith Bridges], Trisha [Angela Bath], and Sam [Denise Stearns] — decide for a weekend get-together with their respective boyfriends, planning a quiet escape from the holiday bustle. That night, their classmate Cynthia and her boyfriend are murdered outside the school by an assailant with a hunting knife.
The group’s uneasy celebration turns grim as they coerce Nancy into giving their housemother, Mrs. Jensen [Kiva Lawrence], milk laced with sedatives to keep her asleep. With the house quiet, they head to a nearby airstrip to meet the men who’ve flown in on a private plane: T. J. [William Lauer], Alex [Forrest Swanson], Tom [Solomon Trager], and Blake [Jeff Butts]. Inside the living room, conversations drift from old memories to present danger, until Trisha slips away to the kitchen to fetch more beer. A figure in a Santa Claus suit and mask confronts her, slitting her throat in a chilling moment that shatters the group’s fragile sense of safety. When Trisha does not return, Tom goes to find her and is chased outside by the killer, who knocks him unconscious with a rock and then buries the bodies in the school’s garden.
The violence escalates quickly. Sam and Blake withdraw to the parlor, only to be interrupted by the killer, who struts in a decorative suit of armor, shoots Blake with a crossbow, and decapitates Sam with an axe. Nancy’s dread deepens as she encounters Ralph, the groundskeeper, who warns that something evil is about to happen. Melody, meanwhile, flirts with Alex in her bedroom and—emerging from a different, more intimate impulse—gives him a handjob, heightening the tension and secrecy that already gnaw at the group.
The morning after, Nancy discovers Ralph’s corpse in the woods, and a detective named Polansky [Sam Shamshak] begins to take the case seriously. He suggests that the remaining students stay indoors to finish the weekend, fearing that the missing might be victims—or possibly perpetrators—in Ralph’s death. That night, the danger reaches the house again when Jim [Bill Martin], a police officer stationed outside, is slain by the killer with an axe. Inside, Leia lures another officer, Dan [Jay Rasumny], into the bathroom, where she finds Sam’s severed head hanging from the shower head. Dan opens the door, only to be stabbed to death from behind. Leia’s psyche begins to unravel; she staggers post-trauma, dancing and humming as if the night’s horror has left her speechless.
Outside, Melody and T. J. share a moment under a tree, but the killer—still unseen—strangles T. J. with a wire garrote from a hiding place above. Melody escapes back inside to find Nancy, Alex, and Leia; together they confront the looming menace in a Santa outfit. The killer is revealed to be Mrs. Jensen, driven by vengeance for her daughter’s death in the prank two years earlier. Melody scrambles toward the airstrip and pleads with the sleeping pilot beneath the plane to take her to safety; their plea ends in tragedy when an unseen Santa figure starts the engine, slicing them to pieces with the propeller.
Back at the school, Nancy is chased by Mrs. Jensen to the balcony. In a final struggle, Mrs. Jensen is hurled to her death. A second Santa figure emerges: Polansky, who reveals himself as Jensen’s husband. He attempts to strangle Nancy, but Alex [Forrest Swanson] kills him with a crossbow bolt. Grasping for safety, Nancy and Alex flee the school together, leaving Leia alone on the balcony, still dancing, her mind a volatile echo of the night’s horrors.
