As guests arrive for a party at her Irish mansion, Lady Athelinda Playford has decided to cut off her two children without a penny and leave her vast fortune to an invalid who has only weeks to live. Among her visitors are the famous Belgian detective Hercule Poirot and Inspector Edward Catchpool of Scotland Yard. Neither knows why he has been invited --- until Poirot begins to wonder if Lady Playford expects a murder. But why does she seem so determined to provoke a killer? And why --- when the crime is committed despite Poirot's best efforts to stop it --- does the identity of the victim make no sense at all?