JACK AND ANNIE continue their quest for the secrets of happiness secrets they need to save Merlin This time the Magic Tree House takes them to the one continent they haven t visited before Antarctica What can they hope to learn about happiness in such a barren place Only the penguins know for sure Jack and Annie are about to find out Children s LiteratureDuring what seems like just an ordinary day a light shoots through the sky over Frog Creek Pennsylvania and immediately Jack and Annie know that the magic tree house is back They also know that it is likely that they will be sent on another mission Once at the tree house the children discover that this mission is not an ordinary one This mission is the culmination of their three previous missions and can potentially save Merlin s life or not They must find the fourth secret of happiness to present to the dying Merlin After receiving the necessary details in the form of a riddle Jack and Annie soon find themselves properly equipped on the continent of Antarctica of all places They also find that they are there in the present and not the past like usual Between the riddle the location and the era it seems to them like this mission is going to be one of the most difficult yet But true to their tenacious spirit Jack and Annie overcome one obstacle after another in this unforgiving setting to discover for themselves and for Merlin the final precious gift that they seek Once again Mary Pope Osborne has crafted a simple but magical story that weaves together aspects of legend history and science into one cohesive tale Magic Tree House series 40 Reviewer Trina Heidt - from Amzon