Captain Herman Suvorin (Anton Walbrook) is a Russian soldier in St Petersburg in 1806. He comes from a working class background, and is consequently spurned by his wealthier fellow officers. Suvorin begins gambling, playing the card game Faro (card game). He is told of an aged countess (Edith Evans), who allegedly Deal with the Devil in exchange for success in playing Faro. Suvorin seduces her ward (Yvonne Mitchell) as part of a plan to learn the countess's secret of success.