While dining out in London one evening, Hercule Poirot notices a young woman, Jacqueline De Bellefort dining and dancing with her fiancé, Simon Doyle ,Poirot also notices that Jakie is very in love with Simon. The next day, Jacqueline takes Simon to meet her best friend, wealthy young heiress Linnet Ridgeway, in the hopes that Linnet will offer Simon a job. Three months later, Simon has broken off his engagement to Jacqueline and married Linnet.
Poirot happens to encounter the couple on their honeymoon to Egypt, where he himself is on holiday. At their shared hotel in Cairo, Poirot sees an apparent chance meeting between the Doyles and Jacqueline. Afterwards, Linnet approaches Poirot and confides that Jacqueline has been stalking them since they were married, which is antagonizing both of them. Poirot says the Doyles have no legal recourse, but tries to reason with Jacqueline in private, urging her to let go of her attachment to Simon and not "open your heart to evil." Jacqueline refuses to listen, confiding that she has been dreaming of killing Linnet.