context: The film begins with a meeting between wealthy heiress Linnet Ridgeway (Lois Chiles) and her close friend Jacqueline de Bellefort (Mia Farrow). Jackie wants her fiancÃ©, Simon Doyle (Simon MacCorkindale), to work for Linnet, but he and Linnet have a whirlwind affair and end up marrying. While honeymooning in Egypt, they are continually hounded by the jilted Jackie. In an attempt to get away, the Doyles pretend to go to the Cairo Railway Station before backtracking to board their booked cruise on a Nile paddle steamer, the S.S. Karnak.
  When the passengers venture on-shore to examine a nearby temple, a large stone is pushed off a pillar and narrowly misses Simon and Linnet. They again encounter Jacquie, who boards the ship having ignored the warnings of detective Hercule Poirot (Peter Ustinov) to stay away, revealing that she carries a small pistol. After a late-night game of cards in the ship's lounge, Jackie confronts Simon. In a drunken rage she fires and shoots him in the leg. The next morning, Linnet Ridgeway is discovered murdered in her cabin, shot in the head by a similar weapon. A "J" is written in blood on the wall from Linnet's finger, appearing to implicate Jackie. Also, Jackie's pistol is missing. Poirot and his friend Colonel Race (David Niven), also a passenger, take it upon themselves to investigate.
  Most of the other passengers on board the ship are found to have had a motive for murdering Linnet: Mrs van Schuyler (Bette Davis, an elderly American kleptomaniac, displayed great interest in her valuable pearls; her nurse Miss Bowers's (Maggie Smith) family was financially ruined by Linnet's father years earlier; Andrew Pennington (George Kennedy), Linnet's American lawyer, embezzled money from the Ridgeway estate; Swiss psychiatrist Ludwig Bessner (Jack Warden) was facing exposure by Linnet concerning his unorthodox methods; romance novelist Salome Otterbourne (Angela Lansbury) was being sued for libel by Linnet due to a likeness between her and one of Mrs Otterbourne's characters; her daughter Rosalie (Olivia Hussey) was protective towards her mother; Jim Ferguson (Jon Finch), a Communist, resented Linnet's lifestyle; and Louise Bourget (Jane Birkin), Linnet's maid, was bitter due to her mistress' refusal to grant her a dowry for her wedding to an already married Egyptian man. Jackie is a natural suspect but is the only one who has a solid alibi, having been given morphine and observed by Miss Bowers all night (alcohol and Morphine would, in Nurse Bowers's words, sink the Titanic). Simon Doyle was also unable to commit the crime due to his leg wound. Poirot is convinced someone on deck overheard the argument, removed the gun and used it to kill Linnet. Poirot confronts each guest aboard the Karnak in turn and explains how each had a reason to want to kill the heiress.
  Soon a bundle is found in the Nile. The missing pistol is wrapped in Mrs. van Schuyler's stole, which had a small bullet hole in it. A handkerchief was also included, stained with blood. Linnet's pearls are also discovered to be missing. When interrogated, Mrs. van Schuyler denies ever having touched them. Shortly after this, the pearls are found on Linnet's body, so Poirot deduces Mrs van Schuyler has put them there.
  While Poirot and Race conduct their investigation, the maid Louise is murdered. Her throat has been cut with one of Dr. Bessner's scalpels and a fragment of a banknote is found in her hand. Poirot realises she probably saw the murderer coming out of Linnet's cabin and attempted to extort money in return for her silence. Salome Otterbourne claims to have seen Louise's murderer and is about to tell Poirot and Race when she is shot in the head through an open cabin door with Pennington's revolver, too large to have been used on Linnet.
  With several suspects eliminated, Poirot gathers everyone in the saloon, where he reveals the solution â Simon Doyle murdered his wife, with Jacqueline as his accomplice. Poirot reveals that Simon and Jackie were still lovers, and his marriage to Linnet had been cleverly plotted to gain her money. They easily faked Simon's shooting, leaving him free to murder Linnet while Bessner was being fetched by Ferguson and as Jacqueline was attended to by Miss Bowers. Simon was left alone long enough to run to Linnet's room, shoot her in the head, return to the lounge and shoot himself in the leg through the stole â a third shot of which no one was aware. Jackie covered up. She planted money for Louise, stole the knife then killed her. She stole the revolver and killed Salome Otterbourne. Simon and Jackie point out that Poirot has no proof, so Poirot convinces Simon that his hands could be tested for grains of gunpowder removed with wax. Realising that they have been found out, they confess, and in a final love embrace, Jackie covertly takes back her pistol and shoots Simon, then herself.
  At the end of the cruise, Poirot says goodbye to the remaining guests, reveals that the test was made-up, and Rosalie and Ferguson announce that they are engaged.
question: What are Jaqueline and Simon doing in the beginning of the film?
answer: Meeting with Jacqueline's friend Linnet