The story is set in Market Basing, Berkshire and centers on Emily Arundell, a wealthy spinster surrounded by grasping young relatives. She is injured by falling down a staircase, and everyone believes that she tripped over a ball left by her pet fox terrier, Bob. Emily later dies of natural causes (or so it is believed), and her estate is unexpectedly left to her companion, Miss Lawson. A letter written before her death to Hercule Poirot by Emily arrives too late to save her, but puts Poirot on the case.
