Magic Tree House:Winter of the Ice Wizard
Merlin the magician and Morgan le Fay have disappeared, and in order to find them, Jack and Annie journey with their friends Teddy and Kathleen to the Land-Behind-the-Clouds, a frozen kingdom of ice and snow. There they must overcome their fears and solve the Ice Wizard's riddle, because if Jack and Annie don't complete their mission in time, Merlin and Morgan will disappear forever!