From the introduction:
Welcome to Rats in the Sewers, the first 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 1: Rats in the Sewers, the PCs are asked to solve a series of mysterious disappearances. They follow the trail into the sewers, find the goblins responsible, and learn that they are selling the bodies to a shadowy group of humans.