During a Monopoly match with Hastings, Poirot is interrupted by an aristocratic banker to investigate the disappearance of a client. The client, who was supposed to sell the bank a map to a lucrative silver mine, is found murdered, and a young stockbroker is implicated in the crime. Poirot works his way through a convoluted web of clues to confront the killer at an opium den. ~ Rebecca Flint Marx, All Movie Guide