Pathfinder: GameMastery Module D3: The Demon Within

A dungeon adventure for 11th-level characters.
For years, the knights of Mendev have held back the evil locked inside the Worldwound, a vast, demon-tainted landscape. Every few years, they anoint a new protector, a sacred guardian charged with pitting his will against the teeming hordes bent on devouring the very souls of the living. This year, something has gone horribly wrong, and now a bloodthirsty demonic army has overrun the ancient fortress, and threatens to pour into the surrounding countryside.
This adventure is set in Mendev, the site of the largest crusade in the Pathfinder Chronicles Campaign Setting, but it can be easily adapted for use in any setting. For more information on this enduring struggle, check out the Pathfinder Chronicles Gazetteer.
Written by Stephen S. Greer and Tim Hitchcock
GameMastery Modules are 32-page, high-quality, full-color, OGL-compatible adventures for use with the world's most popular fantasy RPG. All GameMastery Modules include four pre-made characters so players can jump right into the action, and full-color maps to enhance play.