From the introduction: Within the small town of Rivercrest, near the Witherbark Forest, a terror has crawled from the darkness of the past. The bodies of several townsfolk have been discovered in their homes with a darkened shadow emblazoned on the walls above where they lay depicting the horrific act. The killings dredge up memories of a person, long dead, that terrorized the town over a decade ago. Now, the Mayor and Watch Captain of Rivercrest have decided to seek help from adventurers in order to stop whatever creature is responsible. The PCs are directed to the site of the latest murder and allowed to investigate. Throughout the adventure they will question witnesses, and find clues to the identity of the killer. Their investigations will draw the attention of the creature responsible, a bugbear named Mowg, that feeds on the fear of the townsfolk as well as their flesh. Eventually the PCs will track Mowg to his home in the wilds and do battle with the twisted creature.