Jacqueline de Bellefort, a feisty and clever young woman is engaged to be married to Simon Doyle. Simon is square jawed and loveable but not very well off. When he loses his job, Jackie appeals to her old school friend, the rich and beautiful America heiress, Linnet Ridgeway, to give Simon a job. Linnet does more than that. Much to Jackie's despair, Linnet seduces him and marries him herself. Seeking her revenge, Jackie follows the happy couple around, haunting every honeymoon destination. It is in Egypt where they bump into Hercule Poirot. Linnet appeals to Poirot for help but Poirot is on holiday. He does however agree to talk to Jackie and when he does get the opportunity he finds her so grief stricken that she has a gun, and is fantasizing about putting it to Linnet's head and pulling the trigger. Poirot warns her to stay away and not let evil into her heart as there will be no turning back. The Doyles devise a secret plan to evade Jackie and book themselves on to a Nile cruise, but they are devastated when they discover her on the sun deck. Poirot is deeply concerned by events. The other passengers are a mixture of well to do European and Americans. There is Mrs Allerton and her enigmatic son Tim; Salome Otterbourne, a writer with a drink problem and her depressed daughter Rosalie; Dr Bessner, an Austrian Doctor, an aristocratic Communist called Ferguson and a vicious American society woman called Miss Van Schuyler, who is always attended by her sweet niece, Cornelia. By apparent coincidence, Linnet has also bumped into her American guardian, Andrew Pennington. Linnet implores Poirot to help her telling him she is surrounded by enemies. Could there be someone else aboard that bears Linnet a grudge as well as Jackie? On a trip to shore, Linnet narrowly escapes a boulder falling from a temple. Poirot scours the horizon. Was it an accident or an attempt on Linnet's life? Poirot is surprised but relieved to discover that Jackie was nowhere near the incident. Poirot is delighted as his old friend Colonel Race joins the party. Race is full of anticipation as something always happens when Poirot is around. That night Poirot feels unusually sleepy and retires early. Jackie, drunk and emotional, causes a scene in the bar and then fires a shot at Simon. She is immediately remorseful. In tremendous pain Simon pleads for Jackie to be taken away and given a sedative and that no one should worry his wife. Dr Bessner is woken to tend to the wound and Cornelia is asked to look after Jackie for the night. The next morning Linnet is found dead, shot through the head with the letter J scrawled in blood on the wall next to her. Poirot and Race set to work. They examine the body and Poirot notices that Linnet's valuable pearls are missing. He interviews all the passengers and thinks that perhaps Rosalie is holding something back. The gun is found in the river wrapped in Miss Van Schuyler's missing scarf. Then Linnet's maid is found dead. Poirot notices a fragment of money in her hand. Was she trying to blackmail the killer? Mrs Otterbourne then realises that she must have seen the maid's killer, and just as she is about to reveal who it was, she is shot in the back of the head. Poirot begins to piece it all together, and establishes many of the passengers have hidden secrets. By noticing the burns on Miss Van Schuyler's scarf and the fact that there were burns on Linnet's skin, he realises that there were more shots fired on the night than could be accounted for. He then reveals the terrible truth - but the outcome is still shocking.