Crime novelist Ariadne Oliver again turns to Hercule Poirot, this time to solve a case the police consider closed. Olivers interest in the murder-suicide of General and Lady Ravenscroft is more than academic: Celia Ravenscroft is her goddaughter. This is one of Poirot's most daunting cases  even he begins to doubt he can solve it  since the investigation relies on memories from years earlier.