In The Mystery of the Blue Train by Agatha Christie, an heiress is murdered on a train to the French Riviera. Ruth Kettering, an American heiress, is traveling on the Blue Train to meet her lover. She is carrying a rare ruby, The Heart of Fire, that her father gave her. The police assume the murder was a simple train robbery.

The retired detective Hercule Poirot is also on the train and helps solve the case.