Captain Hastings, wounded at the front, is recuperating at Styles Court in Essex. The house belongs to the Inglethorpe family, friends from his childhood. When Emily Inglethorpe is found poisoned, it is fortunate for Hastings that he bumps into his old friend Hercule Poirot, who can help to solve this horrible murder.The evidence seems to point to one particular family member, and it is up to Poirot, through his methodical investigations, to prove that the real murderer is someone else entirely.