Captain Arthur Hastings, invalided in the Great War, is recuperating as a guest of John Cavendish at Styles Court, the 'country-place' of John's autocratic old aunt, Emily Inglethorpe -- she of a sizeable fortune, and so recently remarried to a man twenty years her junior. When Emily's sudden heart attack is found to be attributable to strychnine, Hastings recruits an old friend, now retired, to aid in the local investigation. With impeccable timing, Hercule Poirot, the famous Belgian detective, makes his dramatic entrance into the pages of crime literature.