A One-Round Living Greyhawk Keoland Regional Adventure
From the introduction:
The cousin of the Viscount of Nume Eor has gone missing. Last reports have him headed into the Hool Marsh. The tiny village of Haven is located nearby, and the refuge for half-orcs and half-elves might be able to help find him.
A "Death in the Hool" adventure for characters level 1 - 8.