Billy is working for his father at the Old Cooper place. During the renovation Billy discovers there is more to the property than an old house, a creepy garden shed and an over grown back yard. 

It all starts when Billy’s rock filled wheel barrow rolls over a small hole in the ground and crashes down into a much bigger hole. This leads to a clue that draws Billy into an ancient mystery. 
He wants to solve the mystery himself and even keeps his discoveries from his best friend Jackie. 

Jackie wants to build a tree fort at the back of the property overlooking the freeway. Billy agrees and he and his friends secretly turn it into the best tree fort ever. 
 
On their first night in the tree house they see a strange event that will lead Billy to a dangerous encounter with some very bad people while on a quest to solve the mystery of the Cooper Place.