How to Betray a Dragon's Hero Hodder children's books

This book will be a hit with children and adults alike. High up in the treacherous mists of the Murderous Mountains, Hiccup and the Company of the Dragonmark are in hiding. The witch's Spydragons are guarding the shores of Tomorrow - but Hiccup is determined to become King of the Wilderwest. Can Hiccup dodge the dragons and steal the King's Things back from Alvin before the Doomsday of Yule? And is there a traitor in Hiccup's camp who in the end will betray them all?