Abby Hunter and Stacy Henry are building a tree house—with a little help from Stacy’s grandpa. When the hideaway is finished, the girls discover that a very cool three house can cause very BIG trouble. Especially when they start posting signs that read Definitely No Boys Allowed! What will happen to their faithful club motto: "The Cul-de-sac Kids stick together"? Is this the end for Abby’s club on Blossom Hill Lane?