Elephants Can Remember

"Hercule Poirot stood on the cliff-top. Here, many years earlier, there had been a tragic accident. This was followed by the grisly discovery of two more bodies--a husband and wife shot dead. But who had killed whom? Was it a suicide pact? A crime of passion? Or cold-blooded murder? Poirot delves back into the past and discovers that old sin leave long shadows"--