The Mystery of the Blue Train

Book #6 in Agatha Christie's Poirot series. When the luxurious Blue Train arrives at Nice, a guard attempts to wake serene Ruth Kettering from her slumbers. But she will never wake again, for a heavy blow has killed her. The prime suspect is Ruth's estranged husband, Derek. Yet Poirot is not convinced, so he stages an eerie re-enactment of the journey, complete with the murderer on board.