On this side of the sky, Mona and her kid sister, Bird, hide in the woods each day because it's far better than being home. But then there's the other side, the side Bird dreams of while she sits in the tall trees she climbs to get away from a life devoid of love. Bird may be eight, but her mind's only five, and Mona has to babysit her most of the time. All their father can do when he gets home is lie on the couch and watch TV, and with another baby on the way, it seems like Mona's mother is always too occupied with her own problems and misery to pay any attention to her. They don't have many friends, but Mona and Bird have always had each other and the hideout of the hidden lake to run to when they needed to escape from mothers and fathers and teachers and bullies and the friends they want and the friends who need their help. But then Mona and Bird witness something terrible in the woods, and suddenly life changes forever for Mona and the others trapped on this side of the sky.