The Underwood children have been told their whole life not to go into the forest behind their home. The thick underbrush causes people to become confused and lose their way.One afternoon, while sitting in a tree house in their backyard, Elm, Willow, and Randy saw bluish-green lights glowing in the forest. They scrambled down the ladder and slipped into the woods. They ventured deep into the forest until they came to a majestic live oak tree covered in Spanish moss. As they stood in awe, the roots of the tree entangled their legs and pulled them underground.They found themselves in a mysterious world they never knew existed. A place with alien landscape, dangerous creatures, and magic. Time is running out-their food is dwindling. If the map Elm found is correct, it could be a very long time before they find their way home.