As autumn begins, Moss and friends travel to their former home in Ash Row, to find the rare mortal child who can both see and talk to them. The tiny beings know they should be brave and talk back–this is their chance to help reverse the fading of ancient Cumulus, who has now almost disappeared entirely. But they soon realize fading is connected to their role in the world ... Can the Hidden Folk prove that guardians of the Wild World are needed after all?