Tar Pits of the Bone Toilers

From publisher blurb:

A new trade route is being sought through the Dalgarian Canyonlands, pass the friendly Kharazan, Village of Plenty. But the last two expeditions have never returned and the merchants are getting anxious for the new route, causing bags of gold to exchange hands.

Meanwhile, the ancient portal, the Maw of Ghormaug, has opened once more and invaders, ‘bone men’, are beginning to take over territory. No one is safe. Left unchecked, these lands are destined for horror and ruin, unless a brave party steps up to the challenge.

An adventure for Levels 5-8 for Labyrinth Lord, Labyrinth Lord Advanced Edition Companion ruleset and other OSR rulesets.