Rachel's cousin is holding a summer fancy dress ball in a Scottish Castle and Rachel and Kirsty have been invited along. There's lots of preparation for the party and Rachel and Kirsty are looking forward to helping out and exploring the castle and its grounds, as well as being very excited about the dressing up part!But Jack Frost is threatening to spoil the party completely. He was planning to hold a goblin party in that same castle, and he's not going to let those pesky humans get in his way. In fact, he plans to steal the items that the Fancy Dress Fairy needs to make sure the ball is a success, and ruin the party, so that his 'Goblin Reunion' can take place just as he wanted. Rachel and Kirsty must help Flora the Fancy Dress Fairy to rescue her three magic items and make sure that Jack Frost and his naughty goblins don't ruin Fancy Dress parties forever!