The great detective Hercule Poirot, who was in Istanbul, returns to England on the famous Orient Express, carrying with him people of seemingly every possible nationality. One of the passengers, an unpleasant American named Ratchett, offers Poirot the chance to be his bodyguard, believing he is being assassinated. The famous Belgian dismisses this absurd request. The next day, the American is found dead in his compartment, the doors closed and the window open. Poirot immediately begins his investigation and discovers that the compartment is full of all sorts of clues pointing to... practically every passenger on the Orient Express. To make matters worse, the train becomes completely stuck in a snowdrift in a deserted area. Poirot must find the killer before the express continues on its journey.