The Warden and the Wolf King By Andrew Peterson

All winter long people in the Green Hollows have prepared for a final battle with Gnag the Nameless and the Fangs of Dang. Janner Kalmar and Leeli–Throne Warden Wolf King and Song Maiden of Anniera–are ready and willing to fight alongside the Hollowsfolk but when the Fangs make the first move and invade Ban Rona the children are separated. Janner is alone and lost in the hills