When Jack and Annie are whisked away by the magic tree house, they find themselves in the freezing Ice Age, dressed only in their swimsuits. On a quest to find a special object beginning with the letter M to free Morgan le Fay from her spell, the siblings nearly freeze in the snow before discovering shelter in a cave. There they meet a young caveboy who shares mysterious cave paintings and gifts them a mammoth-bone flute. Racing across the icy landscape, riding woolly mammoths, and escaping a fearsome sabertooth tiger at sunset, Jack and Annie discover the power of courage, friendship, and music.
