Keep on the Borderlands — Ru Emerson

The keep has fallen on hard times.

Raiders hatter the outer walls.

Hordes of goblins and ores roam the countryside, attacking trade caravans and killing merchants.

A mysterious stream of dark-robed priests travels through the keep's walls, heading out into the wilderness, never to be heard from again.

Amid all this trouble, a band of hired adventures journeys to the Caves of Chaos to stem the tide of turmoil once and for all.