"A celebration of the winter solstice and the Yuletide season. As the sun set on the shortest day of the year, early people would gather to prepare for the long night ahead. They built fires and lit candles. They played music, bringing their own light to the darkness, while wondering if the sun would ever rise again"--

Jack and Annie, joined by Teddy and Kathleen (from earlier books), travel in the Magic Tree House to a land of snow where the Ice Wizard has captured Morgan and Merlin. The four friends must find the Ice Wizard's missing eye - or is it really his heart that is missing? Jack and Annie are joined by Teddy and Kathleen as they travel to the snowy Land-Behind-the-Clouds, where they search for the eye of the Ice Wizard and attempt to help Merlin and Morgan....

When the goddess Artemis disappears while hunting a rare, ancient monster, a group of her followers joins Percy and his friends in an attempt to find and rescue her before the winter solstice, when her influence is needed to sway the Olympian Council regarding the war with the Titans.