Hercule Poirot is vacationing in Egypt and boards a luxurious Nile steamer. Among the passengers are wealthy heiress Linnet Ridgeway and her new husband, Simon Doyle. Simon's embittered ex-fiancée, Jacqueline de Bellefort, appears unexpectedly and begins stalking the couple, creating tension with each encounter. As Poirot attempts to mediate the situation, it becomes clear that nearly all the passengers harbor some form of animosity or hidden agenda against Linnet.

One night, Linnet is found murdered, and Poirot is compelled to investigate. With a myriad of potential suspects, Poirot meticulously unravels each individual's alibi and hidden motives. He discovers a tangled web of enmity, jealousy, and deceit among the passengers. As Poirot delves deeper into the complex relationships and secrets of those aboard, he pieces together critical clues that bring him closer to solving the crime.