From the back of the book: Beneath the Earth, under a Subterranean Sun, is a realm of ambulatory toadstools, scheming and machinating and living their little toadstool lives. Sometimes, they explore the surface. This book gives all the details of these underworld interlopers in order to enrich your not-in-a-Mushroom-Kingdom campaign. Sounds of the Mushroom Kingdom: Putting the Fun in Fungi!