This is book number 1972 in the Hercule Poirot Mysteries (Audio) series.
A classic Hercule Poirot investigation, Agatha Christie's Elephants Can Remember has the expert detective delving 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."