From the front cover: The wizard and warrior disappeared, leaving their vast underground complex behind. Years later a band of adventurers discovered the fortress and caverns and cleared out the evil that had taken up residence. But what happened to the mysterious owners and what was their fate. A single clue had been discovered and it will surely reveal the Legacy of the Unknown! This module has two booklets inside: a 24 page overview and rules/monsters/spells section and a 44 page adventure booklet.