'So who killed whom?' That's the question writer Ariadne Oliver asks. But this time, it's not connected to the plot of a new novel, but to a real-life crime from her own past. Ariadne is haunted by the mysterious death of a married couple, her friends, twelve years ago. At the time, this tragedy was ruled a double suicide. But Mrs. Oliver believes otherwise... And so she turns to her old acquaintance, the great detective Hercule Poirot, for help. The case intrigues the tireless Belgian, and he immediately takes it on. For Poirot, the old crime has lost none of its relevance, for he knows from personal experience that murder, like history, has an unpleasant tendency to repeat itself...