The movie begins in an idyllic family Christmas setting but quickly transforms into a nightmare. Billy, a traumatized child, witnesses a horrifying incident when a thief disguised as Santa Claus murders his parents on a December night. From that moment on, Billy's life takes a dark turn. He grows up in an orphanage where he is tormented by the strict and cruel nun who runs the place, causing him even more anxiety and confusion about the holiday.
Years later, now a young man, Billy tries to lead a normal life and secure a job at a comic book store. But the trauma from his childhood continues to haunt him. As Christmas approaches, old wounds resurface, and after a series of traumatic events and the pressure from his surroundings, Billy succumbs to his darkest instincts. In a macabre twist, he becomes a killer who roams dressed as Santa Claus, unleashing his rage upon those who cross his path.
As his killing frenzy intensifies, the characters around him struggle to stop him. With an essential ingredient of Christmas horror, this story explores the vulnerability of innocence and the psychological impact of trauma, all wrapped in a haunting atmosphere. As the lights flicker and the snow falls, Christmas becomes a backdrop for visceral terror and unleashed violence.