From the back of the adventure:
Long ago, the drow unwittingly built a small enclave above a subterranean realm where a corrupted finger of the Shadowfell touches the world. Once home to a vampire exarch of Orcus, this dead zone still contains unspeakable malevolence that seeks to create terrifying new soldiers for the Demon Prince of the Undead
Includes a 32 page guide that contains an adventure overview, new monsters and full-color illustrations of sights and scenes in the adventure; a 64 page encounter guide detailing the horrors of the Demon Queen's Enclave; and a double sided battle map