How to Betray a Dragon's Hero 11 (How to Train Your Dragon) by Cressida Cowell

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