A One-Round Living Greyhawk Keoland Regional Adventure
From the introduction:
More vile and unnatural creatures have been coming out of the Rushmoors of late, and the surrounding villages are fearful for their lives. Holphin Neheli sends out a call to the local adventurers to go into the swamp and find the cause of the undead hordes.
Part 2 in the Crowning Glory cycle, for characters level 3 - 8.