The death of a weathy widow is believed to be an accident until her future husband is killed. The police bring in Hercule Poirot to help with the investigation.

Number One was the greatest criminal brain of all time; Number Two was a multi-millionaire; Number Three was a beautiful Frenchwoman; and Number Four was "the destroyer," the ruthless murderer with a genius for disguise, whose business it was to remove those who interfered with his masters plans. These four, working together, aimed at establishing world dominance. Hercule Poirot was preparing for a voyage to South America when an uninvited guest,...

Beautiful actress Jane Wilkinson asks Poirot to clear her of suspicion when her husband is murdered, but she had previously tried to hire him to get rid of her husband.