Chess world champion Mirko Czentovic is travelling on an ocean liner to Buenos Aires. Dull-witted in all but chess, he entertains himself on board by allowing others to challenge him in the game, before beating each of them and taking their money. But there is another passenger with a passion for chess: Dr B, previously driven to insanity during Nazi imprisonment by the chess games in his imagination. But in agreeing to take on Czentovic, what price will Dr B ultimately pay?