A wealthy British heiress honeymooning on a Nile cruise ship is stalked by a former friend, whose boyfriend she had stolen before making him her new husband.
While on their honeymoon in Egypt, newlyweds Simon Doyle and Linett Ridgeway are constantly harassed by Simon's ex-fiancée Jackie De Bellefort who feels her ex-best friend has stolen the love of her life. A holidaying Hercules Poirot counsels Jackie to put an end to her antics, fearing that all of this can only end in tragedy. When one of the passengers is killed while on a cruise down the Nile, Poirot must sift through an odd assortment of passengers, all of whom may have something to hide. There is Linett's financial advisor from the US, her French maid who clearly has something to hide, the Austrian doctor who keeps mostly to himself and the left leaning philosopher who despises the rich.
Hercule Poirot is on holiday in Egypt. Part of his travels includes a trip down the Nile on a passenger boat. On board are a mixed selection of characters. Most notable is a wealthy heiress, Linnet Ridgeway, and her husband, Simon Doyle. Also on board is the woman Mr Doyle left for Ms Ridgeway, Jacqueline De Bellefort. In revenge for Ms Ridgeway stealing the love of her life, Ms De Bellefort has been openly following Ms Ridgeway around and generally irritating her. One night, Ms De Bellefort, in a fit of anger and jealousy, shoots and wounds Mr Doyle. The next morning Ms Ridgeway is found murdered, shot through the head. However, the only two possible suspects - Ms De Bellefort and Mr Doyle - have perfect alibis and could not possibly have killed her. Who did then?
Newly engaged and madly in love couple Jacqueline de Bellefort and Simon Doyle have fallen on hard times. In order to afford getting married, and moreover pay for their planned honeymoon in Egypt, Jacqueline introduces Simon, who has just lost his job in the city, to her old school-friend Linnet Ridgeway in hope that Linnet might help to get him a job. Within weeks of the introduction, Linnet, a rich and achingly beautiful American heiress, has however seduced Simon and married him herself. On Simon and Linnet's honeymoon cruise down the Nile three months later, Jacqueline appears seeking revenge. The next morning Linnet is found dead - shot through the head in her sleep. Jacqueline naturally becomes the head suspect in the case, but she turns out to have a water-tight alibi for the time of the murder. Belgian detective Hercule Poirot, who is also a passenger aboard the cruise, is about to uncover a murder so carefully planned that even he must admit that the murderer has thought of everything. That is, everything except one thing: Hercule Poirot.
- The film opens with Simon Doyle and his fiance, Jaqueline De Bellfort, making out in a bedroom. Afterward, it cuts to the rich Linnet Ridgeway's mansion. Inside Linnet and her Friend Johanna Southwood talk when Louise Bourget, the maid, says that Jaqueline De Bellfort, Linnet's poor friend from Paris, will be arriving. Jaqueline, or Jackie for short, says that she's engaged and has Linnet meet with him in the foyer. Three months later: There is a party in egypt and it seems now that Linnet has married Simon (Later explained that Simon broke up with Jackie to marry Linnet). Hercule Poirot is shown arriving to the party and dances with the struggling author, Salome Otterbourne. Her daughter Rosalie apologizes for her mother's behaviors.Jackie is there and calls out to Linnet which upsets her and Simon. Poirot goes outside for a smoke when Linnet speaks to him about Jackie now stalking them because of the break-up. He sees Jackie standing below and tries to tell her to stop. She drops a pistol and tells Poirot that she would "like to put this pistol up against her head and gently pull the trigger." The next morning Simon and Linnet go on a cruise on the Karnak, hoping to have outwitted Jackie, but only to find that she is there.Linnet and Simon are Distraught at this. One of the Karnak's stop is at a port called Dendera. All passengers disembark and visit the temple of Hawthorne. Linnet is almost crushed when a stone dislodges and falls. Jackie is seen and Simon thought that she pushed it; but the assumption is wrong because Jackie came from a different building. Poirot meets his old friend and colleague, Colonel Race. Poirot being surprised tells him that he thinks something is already starting. Back on the Karnak, that same night, Linnnet, Simon, Race and Linnet's Beneficiary (Andrew Pennigton) play poker when Jackie comes in. She is drunk. Another girl, Cornelia Robson, has decided not to go to bed yet. Jackie orders a server two Gin's altough Cornelia refuses. Linnet, Andrew and Race go to bed. Jackie, Simon, Cornelia, and Mr. Ferguson stay on the saloon. Jackie, after having drunk so much, takes her pistol and shoots Doyle in the leg, injuring him. She kicks the dreadful thing under the chair. Ferguson and Cornelia take Jackie to her room at Simon's insistence, Ferguson getting Dr. Bessner to assist. Dr. Bessner extracts the bullet and gives Simon something to help him sleep. The next morning, Race tells Poirot that Linnet has been shot through the head in her sleep. In the bedroom, Poirot sees a red J on the head of the bed. He assumes that Jackie is the shooter and that as Linnet is dying, she dips her finger in her own blood and wanted to identify the killer(although this death was instant). Poirot now tries to deduce who the killer is.