Murder on the Orient Express is one of Agatha Christie's most famous novels. In it, we find the Belgian detective Hercule Poirot on a steam engine traveling from Syria to London. Everything's fine and dandy, until the train is caught in a snowdrift and one of the passengers is murdered. Cut off from the police, the little Belgian detective is pressed to take the case. He must collect evidence and interrogate the passengers in order to decide who among the strangers on the train would have been driven to murder. Readers follow along with Poirot's investigation and get the chance to use their powers of observation. (Or their "little grey cells," as Poirot would say.) We think you've got a good chance at cracking the case, though the American crime writer Raymond Chandler once cheekily remarked that "only a halfwit could guess it." That said, even if you can't pin the murderer, Murder on the Orient Express offers readers tons of cool stuff to think about, beyond just who has blood on their hands. For example, the novel is really interested in how we define justice as opposed to revenge. That is, when is murder justified and when is it just, well, murder? A juicy question, to be sure. The question gets even more complicated, though, since we don't have a judge or jury on hand or even a court of law to tell us what's right and what's wrong. Instead, the passengers on the train – who are from all different countries and classes – must play those parts themselves. Is justice served in the end? That's a mystery only the reader can solve.