The famous detective Hercule Poirot sleeps peacefully on a Paris-Croydon flight, unaware of what's happening right next to him. He awakens to learn that his seatmate, the elderly Frenchwoman Madame Giselle, has been found dead. Initially, her death is attributed to a wasp sting, but Poirot discovers she died from a poisoned dart. The doctor's conclusion is that she died from a rare poison. There are only ten passengers and two stewards on board—one of whom is the murderer. Poirot himself is also under suspicion—an extremely unusual role for the famous detective.