At a college pre-med student fraternity New Year's Eve party, a reluctant Alana Maxwell is coerced into participating in a prank: she lures the shy and awkward pledge Kenny Hampson into a darkened room on the promise of a sexual liaison. However some other students have placed a woman's corpse in the bed. Kenny is traumatised by the prank and is sent to a psychiatric hospital.
Three years later the members of the same fraternities and sororities hold a New Year's costume party aboard a train. Class clown Ed is disguised as Groucho Marx. Prank ringleader Doc Manley is disguised as a monk. Jackson is disguised as an alien lizard. Doc's girlfriend, Alana's best friend Mitchy, is disguised as a witch. Alana's boyfriend Mo is disguised as a bird. Also along are Carne, the train conductor, and a magician hired to entertain the crowd.
As the train journeys into the icy wilderness, the students responsible for the prank are murdered one by one, with the killer assuming the mask and costume of each murder victim in turn. Carne discovers some bodies and sequesters the students in one car as the train begins its return journey. Alana recalls the prank, and, remembering that Kenny loved magic, suspects the magician is the killer. However the magician has disappeared, and is eventually found impaled inside his sword box.
Alana is sequestered in a locked compartment for her safety, but the killer is still aboard, stalking her. The killer enters the compartment but Alana escapes, and is pursued by the killer through the train. In the final scene, the masked killer is revealed to be Kenny who was disguised half the time as the magician's female assistant. Kenny refuses Alana's apology and forces her to kiss him, but the kiss causes Kenny to relive his memories of the prank, driving him deeper into insanity. Carne rushes to the scene and beats down Kenny with a firemans' shovel, causing him to fall out the open door of the baggage car to his presumable death. His body lands in a nearly frozen river and floats away as the train roars off.
Who discover the bodies?
Carne