From the back of the book:
Tonight, a ceremony of light is taking place on the surface.
Meanwhile, a world away in the city of spiders, a drow matron solidifies a pact with soul-consuming entities who require great sacrifices in trade for unimaginable power. Drow eyes turn to the surface.
This book contains a mega-adventure and setting, taking characters across the surface and into the depths of the world. Adventurers will meet unique denizens, battle horrors of the Underworld, explore epic locations, and fight to stop the rise of the drow.