There's a new boy in the neighborhood, and he's up to something very curious. His next door neighbor, a girl his age with two long braids, peeps around corners and watches as he scavenges wood from the fence between their houses, drags around a hammer and a bucket of nails, and reads a book about living in trees. When she finally works up the courage to say "hi," she finds herself invited to help build the private getaway every child has dreamed of: a tree house. She also finds herself with a new best friend.