**In this exclusive authorized edition from the Queen of Mystery, the expert detective delves into an unsolved crime from the past involving the strange death of a husband and wife.** Hercule Poirot stood on the clifftop. Here, many years earlier, there had been a fatal accident followed by the grisly discovery of two bodies—a husband and wife who had been shot dead. But who had killed whom? Was it a suicide pact? A crime of passion? Or cold-blooded murder? Poirot delves into the past and discovers that “old sins leave long shadows.”