The Queen of Spades (opera)
Hermann, a young officer, sees a beautiful girl in the park and falls in love with her even though  he does not know her.  His friend tells him that the girl’s name is Lisa, and that her grandmother is an old countess who used to gamble (play cards for money) when she was young.  He says that people used to call the grandmother the "Queen of Spades", and that she knows a secret: she knows about the three cards which will always win the card game.