In World War I, a young Hercule Poirot devises a successful strategy to advance his Belgian company, but a booby trap mutilates his face. His lover, nurse Katherine, suggests he grow a mustache to hide his scars. In 1937, Poirot watches blues singer Salome Otterbourne perform at a London club, and sees Jacqueline “Jackie” de Bellefort introduce her fiancé Simon Doyle to her childhood friend, heiress Linnet Ridgeway.
Six weeks later in Egypt, Poirot encounters his friend Bouc, who introduces him to his mother Euphemia, a painter, and to a surprising newlywed couple – Linnet and Simon. Others join their honeymoon trip: Linnet’s maid Louise Bourget; Salome and her niece/manager Rosalie, Linnet’s schoolfriend; Linnet’s godmother Marie Van Schuyler with her nurse Mrs. Bowers; Linnet’s cousin Andrew Katchadourian, who manages her accounts; and doctor Linus Windlesham. Linnet asks Poirot for protection from the obsessive Jackie, who has stalked them to Egypt; he tries to dissuade Jackie, who shows him she carries a gun.
To escape Jackie, the group boards the cruise ship S.S. Karnak, though Linnet tells Poirot she does not trust her guests. During an excursion to Abu Simbel, Bouc confesses that he is dating Rosalie, despite his mother’s disapproval; Poirot shows interest toward Salome. After a boulder nearly crushes Linnet and Simon, the guests return to the Karnak to discover Jackie has boarded. Poirot, overcome by champagne, confides to Jackie that he renounced romance after Katherine died in a mortar explosion. Linnet goes to bed and Simon confronts Jackie, who shoots him in the leg and attempts to shoot herself, but Rosalie and Bouc intervene. They bring Jackie to Mrs. Bowers, while Windlesham treats Simon. The following morning, Louise discovers Linnet has been shot in the head, and her valuable necklace has been stolen.
