Many years ago two wealthy adventurers, Rogahn the Fearless and Zelligar the Unknown, built a hidden complex known as the Caverns of Quasqueton. From this base, they conducted their affairs away from the prying eyes of civilization. While of questionable ethical standing, the two drove back a barbarian invasion and gained the support of locals. Eventually, they gathered their own army and went on an expedition against said enemies, where they met their demise.
The player characters (PCs) enter the story at this point, hearing a variety of rumors provided in the module. Each PC knows one or more of the stories although the veracity of them is somewhat questionable. The rumors mostly involve a great treasure hidden somewhere in the Caverns of Quasqueton, which the PCs can enter from a cave-like opening.
A variety of monsters wander through the finished upper level of the dungeon including orcs, troglodytes, and giant rats. The DM checks periodically to see if the group encounters these menaces in addition to the dangers in each individual room. Most of the rooms come with blank spots where the DM fills in whatever monster or treasure is most suitable for their campaign.
The finished upper level served as a home for Rogahn and Zelligar and contains much of their personal possessions. A number of traps await an unwary group. Some of these rooms include an area filled with pools (some hazardous and others not) and a wizard's laboratory.
The randomly generated monsters in the lower, unfinished level differ from those above and include zombies and goblins. Some of the pre-filled rooms on this level include a museum, an arena, and grand cavern, but many of the caves on this level include no description at all and the DM must devise contents for these areas.
The end of the module includes a list of foes and treasure for the group to fight and find. It also includes a list of characters of various classes the group might encounter while exploring the dungeon. Also included are a number of pre-generated characters the group might use to play through the adventure.