Countless books have been written on happiness but remarkably few for those who need it most -- children. Sadie, a lovely little fairy, is never happy. Joy, the queen of all the fairies, learns of Sadie's sorrow and whisks her off to the King and Queen's castle to observe Princess Gabriella "the happiest girl in the kingdom." But when Joy's experiment seems destined for failure, she comes up with a plan that changes Sadie's life forever.