From the introduction:
Welcome to Skeletal Society, the second chapter in the Heroes of Drakonheim trilogy. Heroes of Drakonheim may be played all together or as stand alone adventures. The adventure is set in the fantasy city of Drakonheim, which can be incorporated into any larger fantasy world.
In Chapter 2: Skeletal Society, the PCs discover that the group purchasing the corpses is a cabal of necromancers calling itself the Grey Society. In the process, the PCs may stumble upon a nest of wights, some of the Society’s headquarters, and perhaps a Society initiation ceremony. These encounters lead to a final confrontation with the leader of the Grey Society, who implores the PCs to end their grudge against them. The Grey Society is animating a host of undead to combat an even greater threat. A mighty force of hobgoblins and their allies are marching towards Drakonheim and without additional defenses, the city will surely fall.