When it is discovered that the reigning world chess champion, Mirko Czentovic, is on board a cruiser heading for Buenos Aires, a fellow passenger challenges him to a game. Czentovic easily defeats him, but during the rematch a mysterious Austrian, Dr B., intervenes and, to the surprise of everyone, helps the under-dog obtain a draw. When, the next day, Dr B. confi des in a compatriot travelling on the same ship and decides to reveal the harrowing se-cret behind his formidable chess knowledge, a chilling tale of imprisonment and psychologi-cal torment unfolds