Agatha Christie's Poirot: Death in the Clouds (Part 1 of 2)

Another case for the dapper Belgian slueth. When a notorious blackmailer is murdered on a flight from Paris to London, fellow passenger Hercule Poirot is hot on the trail of the killer. On his return to Paris, Poirot discovers his chief suspect is a mysterious American - an enigma in itself as there was no American on the flight.