There's a secret tree fort and you're not invited! In this hilarious and hugely imaginative sibling story from the creator of the internationally celebrated Ike's Incredible Ink, two sisters are told to go and play outside on a beautiful day. The little sister wants them to play together - but the big sister, instead, wants to sit under a tree with a book. So the younger sister decides to tempt her with a description of her super-cool, super-secret...