Aivars Liepa's page

Found the adventure - it's "Bandits!" from Bastion Press.

https://www.enworld.org/threads/bandits.117908/ gives the good answer

Thank You for checking. Maybe someone else will happen upon this and remembers the title...

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)

PC: Woulff, halfling summoner (unchained) 4
Adventure: Bullywug Gambit sidequest from Madness in Freeport
Location of Death: Black Pete's caves
Catalyst: failed saves agaisnt Black Pete ghost

Players went into the Black Pete's treasury room. Pete's ghost warned them and asked to leave. P{arty alchemist managed to speak of 'aren't you lonely there all alone' (of course he was!) and 'do you want some rom?' (impossible to get for ghost pirate!!!). After ensuing battle, two party members got leveldrained for 2 levels and Woulff totally drained down to 0. Party grabbed his corpse and took a very fast retreat.