From the introduction:
This role-playing game Adventure describes the environs of the Hell of the Devils, situated on the Infernal Plane, Gehenna. It is generally based on the descriptions of the Divine Comedy (Inferno, Purgatorio, Paradiso) by Dante Alighieri, and updates, expands, and completes the 1980 Judges Guild module, Inferno. However the characters find themselves in Gehenna their mission is to escape by traveling down through the ten Circles of Inferno to Lucifer, fixed in the center, then climbing down through the ice to find the return path to the Material Plane. Depending on how and why the players arrived in Gehenna there may also be secondary goals to accomplish. This Adventure describes the physical conditions and challenges of each circle, which can be significant even without the hostile ‘natives.’ It also describes in detail some of the important locations that can be visited, and the most important denizens. The geography of Malebolge is complex and the Games Master will be challenged in running this Adventure, it is advised that only experienced Games Masters attempt this Adventure. Games Masters should carefully read all of this material in advance of their game sessions and become thoroughly familiar with the geography, encounters, unique creatures and their powers.