I was once GMing an adventure but that was about 20 years ago and i no more have the printed book. It was short (no more that 36 pages) b&w printed with only cover in color, by some 3rd party publisher.
Adventure itself was early to mid levels (between 3rd and 7th level PCs, i believe) it's starts as usual 'bandits are stopping and robbing caravans' but unusual is there is no survivors. Once PC start to investigate, they discover some bandit leaders ( i believe there was humanoid bandits, maybe gnolls too) have a parasite on their neck. The investigation leads deep in forest to old hillfort, and then to dungeon under hill, where BBEG is revealed as escaped Osyluth trying to build a base of operation with help of parasite monster taking control of local area by expanding parasite controlled network.
There was one memorable trap in dungeon - sloped hall, with barricade at lower end, and a oil pipe at the top, operated from the other side of wall, that can be opened to make stide slippery, and set on fire as well (unfortunately, together with baricade)
