Complex sentence: Detective Hercule Poirot (Albert Finney) is returning to England aboard the Orient Express, encountering his friend Signor Bianchi (Martin Balsam), a director of the Compagnie Internationale des Wagons-Lits, which owns the line.
Split into simpler sentences: Detective Hercule Poirot (Albert Finney) is returning to England aboard the Orient Express. During the journey, Poirot encounters his friend Signor Bianchi (Martin Balsam), a director of the Compagnie Internationale des Wagons-Lits, which owns the line.