Context: A large group of college students are at a bonfire for the New Year's Eve celebration. All of the pledges are wearing beanies, and one nerd-ish pledge named Kenny (Derek McKinnon) is sent by the fraternity president Doc (Hart Bochner) and his friends up to a room in the frat house where a sorority sister named Alana (Jamie Lee Curtis) is waiting in the doorway. Alana walks inside the bedroom and stands behind the canopy in the dark room. Kenny undressed, sits in bed, and realizes that he is sitting beside a bloated and rotting corpse. Kenny screams in terror and he stands up on the bed and is caught up in the canopy. Alana seems repulsed as Doc and a group of other students rush in and laugh at Kenny.Three years later. A large group of college kids are exiting a bus at a train station. They have a toast celebrating four great years at college as they prepare to board a charted old train for a New Year's Eve costume party. Carne (Ben Johnson), the lead conductor, has the students board the train while he organizes the route with the dispatcher. Carne helps a magician (David Copperfield) and his assistant carry their luggage on board, as a three-person band board the train for the excursion.Nearby, Ed (Howard Busgang) a prankster student and one of the ones involved in the prank against Kenny, walks around with a sword through his stomach. The other students laugh and think its another one of his practical jokes, but he falls down after the people walk away and board the train. An unseen person takes Ed's Groucho Marx costume and rolls his dead body under the train tracks. The train leaves and the lights at the deserted station are turned off. The killer is wearing Ed's costume as he moves around the train.Meanwhile, Mitchy (Sandee Currie) another one of the students involved in the prank against Kenny, is talking to Alana who is graduating early and hopes they will keep in touch.In the back of the train, the magician is talking to his blond assistant about the rowdy college kids and complaining about having to perform his illusions in front of them.In the lounge car, Doc is celebrating with his fellow frat brothers when one of them asks about the now abolished "hog night" and he mentions that something bad happened. Alana enters and tells them that they "put a kid in the hospital" who had a nervous breakdown due to Doc's prank three years ago. Alana then goes to her boyfriend Mo, also involved in the prank against Kenny, where they retire for some alone time.A little later, Mitchy sees 'Ed' and he follows her towards the sleeping berths. He nearly grabs her when Jackson, another of the students involved in the prank against Kenny, appears. Jackson is very inebriated and he offers 'Ed' a drink. In the nearby lavatory, the killer grabs Jackson, lifts up his mask for a second to let him see his face, and slams Jackson's head into the mirror. The killer then changes out of his Groucho Marx costume and leaves the lavatory.Meanwhile, Alana becomes angry when learning that the train party was Doc's idea after Mo told her that it was his. Two of the sorority sisters, Pet and Merry, show up where Pet thinks that her boyfriend, Ed, missed the train, and Alana argues with Mo about learning that Doc had set him up again. Carne, the conductor, shows Doc and Mitchy a car trick he learned form the magician (it is only a gag), and the couple waits for the occupied bathroom. After a few minutes, they leave to find another one.Later, the magician performs his show before the students and afterwards, the rock band appears to play. Alana talks with the geekish class president (who was a pledge in the opening scene). Meanwhile, Doc asks Mo where Jackson and Ed are. Mo does not know and when he asks where did he find the magician, Doc says that he did not hire a magician for the party and wonders 
 Question: Who is the killer?
Output: as a monk