Ten-year-old Persimmony Smudge lives a boring life on the Island in the Middle of Everything, desperately longing for high adventure. But when she overhears a life-altering secret, she suddenly finds herself in the middle of an amazing and perilous journey. Mount Majestic, the rising and falling mountain in the center of the island, isn't actually what everyone thinks it is. And now, it is up to Persimmony and her new friend, Worvil the Worrier, to convince the island's quarreling inhabitants, including the subborn young king, that they must come together to face the truth. The question is, will she be able to make everyone believe this unbelievable tale?