This is a PF homebrewed campaign. It takes place in the lands of Karnoss, specifically in a region of rugged hills, forests and mountainous highlands referred to as the Elderscorn Reach.
The brief overview is that the PCs begin in the Small City of Ravenhurst; a town with its own woes and weals. After a short intro adventure w/in the town they go on missions and quests into the dungeons beneath a nearby ruined castle called Flamenwing. Here they will discover the vast underground base of operations for kobolds who go about the Reach pillaging and raiding. The PCs will also find many other fell creatures and vast wealth to their own peril.
Things will also be happening in the land around the dungeon. These events will influence the PCs missions and their actions will have impact on these outside forces. The party will also have the chance to directly interact with these events through side quests and such.
As the campaign progresses the party will uncover the true history of the megadungeon beneath Flamenwing Castle and the reason for the citadel's construction. The darker forces behind the lords and nobles of these lands will be revealed and the party will be guided to deal with these forces as they become hopelessly entangled in them.