When the luxurious Blue Train arrives at Nice, the discovery of a murdered heiress and the theft of her priceless rubies set off a high-stakes investigation. Hercule Poirot, the renowned Belgian detective, finds himself tasked with clearing the name of the victim's estranged husband, who is the primary suspect in the eyes of the authorities. Poirot must navigate a web of deceit, hidden motives, and false leads among the train's elite passengers to uncover the truth. The narrative follows a classic whodunit structure, utilizing Poirot's methodical observation and psychological insight to dismantle the alibis of those on board.

This novel is widely regarded as a quintessential example of Agatha Christie's mastery of the classic detective genre. Readers often highlight the atmospheric setting of the Blue Train as a standout element that heightens the tension of the investigation. The intricate plotting and the methodical nature of Poirot's deduction process are frequently cited as the primary drivers of the narrative's appeal. While some critics note that the author herself expressed dissatisfaction with the book's construction, it remains a staple for enthusiasts of traditional mystery fiction. The work continues to be analyzed for its structural precision and its contribution to the evolution of the detective archetype.