It's the summer holidays and Rachel and Kirsty are visiting Kirsty's grandma, who lives by the sea. After discovering a magical shell on the beach and being whisked away to Fairyland, the girls discover that the fairies need their help. Naughty Jack Frost has stolen Fairyland's three enchanted pearls and this is causing chaos in the oceans and mixing up daytime and night-time! The girls must help Shannon the Ocean Fairy explore a magical underwater world (meeting many strange and wonderful sea-creatures along the way!), outwit Jack Frost and his goblin henchmen, and return each of the enchanted pearls to their rightful place...