It's full-fledged war as Briar, the rat creatures, and the Pawan army storm the city of Atheia where the Bone cousins, Thorn, and Gran'ma Ben are up in arms to defend the royal city. When Thorn hears a voice urging her to seek the Crown of Horns, she and Fone Bone embark on another dangerous journey as they race to find the one thing that may save them all.