Famous detective Hercule Poirot receives a telegram prompting him to return to London. Since he is in Turkey the fastest possible way to travel back to Britain is on the Orient Express. He is lucky enough that the train is leaving that night, but as he soon learns is also fully booked. Poirot must ask his friend, M. Bouc, a director of the company that operates Orient Express, for help, but all Bouc was able to do is find him a second-class berth, which is still better than finding another connection. While aboard Poirot is approached by elderly American, Samuel Ratchett, who believes his life is in danger and would like to hire Poirot to protect him. The first impression of the American is rather negative, so Poirot refuses. Bouc, who travels only to Italy, gives his first-class compartment to Poirot, it is the compartment next to the one occupied by Ratchett. The train is stopped by a snowdrift near Vinkovci in Yugoslavia and during the night Poirot is disturbed by the commotion in the Ratchett’s compartment. The next morning Bouc informs the detective that Ratchett have been murdered during that night and asks Poirot to investigate the case. While checking the murder scene he finds a note with the words "-member little Daisy Armstrong" on it, which puts his investigation on completely new rails.
Classic Agatha Christie novel, one of the most remembered of her works, mostly due to unusual construction, original setting aboard one of the most famous trains in the world and the complicated mystery Hercule Poirot has to deal with.