Poirot, Collection 3: Death in The Clouds

S4 E2: A particularly ingenious murder is committed on the noon flight from Paris to London. Poirot is on board, but unfortunately he's asleep when the killing takes place. It becomes a matter of pride for him to track down the murderer. Returning to Paris, he discovers his chief suspect is a mysterious American - all the more mysterious because there wasn't an American on board.