"The Ravenscrofts didn't seem that kind of people. They seemed well balanced and placid..." And yet, twelve years earlier, the husband had shot the wife, and then himself — or perhaps it was the other way around, since sets of both of their fingerprints were on the gun, and the gun had fallen between them.

The case haunts Ariadne Oliver, who had been a friend of the couple. The famous mystery novelist desires this real-life mystery solved, and calls upon Hercule Poirot to help her do so. Poirot is now a very old man, but his mind is as nimble and as sharp as ever and can still penetrate deep into the shadows. But as Poirot and Mrs. Oliver and Superintendent Spence reopen the long-closed case, a startling discovery awaits them. And if memory serves Poirot (and it does!), crime — like history — has a tendency to repeat itself.