Alida traveled to Russia as companion to her cousin, Lady Mary, who is engaged to marry Prince Voronski. As she entered the empty ballroom, Alida heard the sound of music. Almost without realizing it, her feet carried her onto the polished floor on which the moonlight shone. She moved round the room, waltzing in an enchanted world. Then, her eyes half-shut with the ecstasy of the moment, she no longer danced alone. Round and round the Prince swung Alida until the music stopped. She had dreamed she would meet such a man, that she would fall in love and her whole world would be changed because of it The Prince's noble good looks thrilled her. His kind words had touched her heart But Alida knew she loved in vain. For the Prince was the man her cousin was to marry, but her cousin has meet another young man on the boat....