Zoe and Astra are together again on magical Unicorn Island, and this time they're on an adventure to the Kingdom Under the Sea, where the sea unicorns live, to try and find a precious spellbook. They know it's hidden at the bottom of the ocean in Sea Dragon Cave. They're sure they'll be able to retrieve the spellbook, as the dragon isn't real - it's just made of stone... or is it?
