In Eastern Europe, two powerful sisters, Mother Rosamund of the North and Mother Carmilla of the South, each have an immortal sprite as a surrogate child: Alastor, a mischievous frost sprite, and Vagatha, a dutiful sprite of the aurora borealis. As they grow, Vagatha yearns for freedom, while Alastor falls in love with Charlotte, a beautiful maiden trapped in a difficult home life with her abusive stepfamily. Alastor wishes to help Charlotte but can only do so by becoming human, a transformation forbidden by his guardian. However, he persuades Vagatha to assist him in escaping heaven to become human, and she eventually seeks her own freedom as well.