When the luxurious overnight passenger train from Calais to the Riviera, known as the Blue Train, arrives in Nice, a guard goes into the compartment of American heiress, Ruth Kettering and attempts to wake her. Unfortunately, she will never wake up, as she is dead, having been killed by a heavy blow to her head, disfiguring her almost beyond recognition. What is more, her precious ruby, known as the 'Heart of Fire', is missing.

The prime suspect is Ruth's estranged husband, but detective Hercule Poirot, who also just happens to be a passenger on the train, is not convinced. He undertakes the investigation of the case by interviewing the girl's ex-husband, her father, her maid, her eccentric cousins and many other unconventional characters as he stages a reenactment of the journey.

Go along for the exciting ride with Poirot as he masterfully investigates this heinous crime. It is a mystery packed with greed, passion, and deceit. It's Agatha Christie at her best.