On Christmas Eve, Billy Chapman, Rohan Campbell, rides in a car with his parents when their path is halted on a desolate road. A man dressed as Santa Claus stalks up and murders Billy’s parents right before his eyes, leaving the young boy alive. The killer—revealed later as Charlie, a janitor at Billy’s grandfather’s care home—is fatally stabbed by Billy’s mother, but Billy experiences a strange, physical touch with Charlie that is followed by a sudden electrical surge that seems to pass between them. After these events, Billy learns that his parents had murdered his grandfather for his money, and he is placed under care.
Years pass, and Billy grows into a wary, nomadic spirit who drifts from town to town, avoiding long-term attachments. Each Christmas season, he begins to hear the disembodied voice of Charlie urging him to “punish” those who are “naughty” and to follow a ritual tied to an Advent calendar, guiding him to commit a killing for every day leading up to Christmas. He carries out these murders while dressed in a Santa Claus costume, a haunting pattern that frames his life.
The story intensifies when Billy, having killed a Christmas-tree grower in a motel, arrives in Hackett and takes a job at a gift shop owned by Mr. Sims, David Lawrence Brown. There, he meets Pamela Sims, and a romantic connection blooms between them, giving Billy a fragile anchor in a world that seems to bend toward violence. As the Advent calendar unfolds, Billy continues his macabre ritual, including an attack at a secret neo-Nazi Christmas party, while reports of missing children circulate and a rumored kidnapper known as “the Snatcher” becomes a public concern. Pam’s father becomes a casualty of the Snatcher’s crime, murdered on camera after investigating a car with a bound child inside.
Pam is determined to see justice done, and Billy offers to grant her “Christmas wish.” On the way to the Snatcher’s location, Billy opens up to Pam about his childhood trauma, recounting the electric surge he felt at the moment he touched the killer and describing how the voice has guided him ever since—an odd, almost paternal presence that reveals the crimes of anyone deemed “naughty.” Pam accepts his explanation and agrees to return to the Christmas tree farm, following Charlie’s cryptic guidance. Inside, they uncover three abducted children drugged and hidden in an underground ball pit. The confrontation turns deadly when Pam is seized by the Snatcher and dragged into the pit.
Guided by Charlie, Billy pursues and kills the Snatcher with a boxcutter, but not without being stabbed in the struggle and gravely wounded. Max Benedict, Pam’s ex whom she had come to distrust, arrives at the scene and fatally shoots Billy. As Billy dies, he reaches for Pam’s hand, and an electrical current again seems to pass between them. Pam regains consciousness after Max’s death and sees flashes of Billy’s past, realizing that Max helped the two tree growers abduct the children. Pam fights back, biting off Max’s nose and killing him with Billy’s axe. In the final beats, Pam hears Billy’s voice—asking whether she’s “ready for this”—and a triumphant, ominous grin spreads across her face, suggesting the ritual may still be unfinished or forever altered by her choices.
