Twelve-year old Maine sixth-grader JoJo Mallory and her two best friends - hockey phenom Trip and uber-geek Marcy - must locate an ancient magical talisman and deliver it to the witches who hold JoJo's father captive in the castle formerly known as Camelot. So said the Leprechaun who mysteriously showed up in JoJo's bedroom one morning. Apparently, JoJo's father led a completely different life in a completely different world before showing up in their waterfront Maine neighborhood and starting a family. JoJo and her friends are challenged with trying to figure out how to save Mister Mallory, all while dodging trouble that comes at them in a variety of forms. Eventually, they solve enough of the puzzle to locate the magical Marble, and JoJo surprisingly volunteers to be the one who wields its power to rescue her dad. In the end, she negotiates a crucial bargain with the evil Pewtris Grimm that opens the door for the next book.