"Masquerade, paper faces on parade," sings the crowd. "Masquerade, hide your face, so the world will never find you." Dressed in a slinky black gown and lace mask, I raise my champagne glass and repeat the lyrics, ones I've heard countless times since I was a child, but never got to join in on before. Dancers pirouette around the audience, cast as the performance's "madames and monsieurs," and butlers lead us through the candle-lit labyrinth of the Paris Opera House.