Katie and the fairies need to save the magic oak tree that connects the human and fairy worlds. But they don't know how much time they have to complete their task. The developer has a daughter, Tiffany, in Katie's class at school. She might know something! But Tiffany is a mean girl who doesn't talk to Katie. To find out what Tiffany knows, Bluebell and Katie change places for a day. While Bluebell tries to act like a human girl, Katie becomes a fairy -- complete with wings! But snarky Bluebell has some trouble fitting in at school. Will trading places get them any closer to saving the tree?