As autumn arrives, Moss, Sorrel, Burnet and Dormer decide to return home to Ash Row to unravel a riddle that might explain why their kind are fading from the Wild World. They have friendship, good sense and humour on their side, but will it be enough to secure a future for the Hidden Folk? Or will they need to go further, and find a way to work with the most unreliable of creatures... humans?