Quick recap
Ruth Kettering, daughter of American millionaire Rufus Van Aldin, takes the Blue Train to the Riviera carrying the Heart of Fire rubies. She's found dead in her compartment, her face battered, and the jewels are gone. Also aboard is Katherine Grey, a modest woman from St Mary Mead who has just come into money and chatted with Ruth. Ruth's debt-ridden husband, Derek, is the obvious suspect. Poirot, on the same train, works out that the crime was set up by Major Knighton, Van Aldin's secretary and a famous jewel thief, helped by Ruth's fake maid, an actress. Derek is cleared, and the book ends with him hoping to win Katherine.
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