The place has many names: the Underdark, Deepearth, the Realms Below, the Night Below, the Lightless Lands. This vast world beneath the surface is home to fabled races such as beholders, cloakers, drow, illithids, and ixzan. Menzoberranzan, the dreaded City of Spiders, is only one of the hidden cities of the Underdark.

This book, compiled by the Underdark's most famous son, Drizzt Do'Urden, lays bare the bizarre societies that lurk in the Realms Below. It includes an overview of the major races of the Underdark, an Underdark survival guide, and details and maps of more than a dozen cities. Discover a drow city constructed entirely of calcified spider silk, a nigh-immortal dwarven king trapped in stone form, and a storehouse of knowledge that rivals Candlekeep. Learn the particulars of the alliance between Manshoon and the beholders of the Anaurian Hive, the ambitions of the true master of Firedrake Bay, and an explanation of the enduring strengths of the beholder cults along the Lake of Steam.