Nina loves having her backpack fairy Sybil around! Nina is the only person who can see or hear Sybil and the two have formed a special bond. But when Sybil unexpectedly disappears, a new fairy named Amanite shows up to take her place. Amanite brings Nina to a magical underwater world, where Nina is magically transformed into a tiny mermaid! But then thigns go horribly wrong when sea monsters decide that Nina look mighty delicious! Where's Sybil when Nina really needs her?