Hercule Poirot is called in to investigate an important diamond that was purchased for the wealthy, arrogant Arlena Marshall, who turns up dead while on her honeymoon with her husband and stepdaughter at a tropical island hotel. It turns out Arlena had made many enemies, and as Poirot heads to the island paradise to sort through the long list of suspects, he finds that even among the rich and famous, murder never takes a holiday.