A One-Round Living Greyhawk Theocracy of the Pale Regional Adventure
From the introduction:
In the days after the Second Battle for Bitterhollow, a great blanket of clouds gathered above the city of Ogburg, blocking the sun and casting the city in a grey haze. A renegade knight has rallied a veritable army to his side hunting the final vestiges of Derro with wanton disregard for those caught in the crossfire. Finally divination on either subject seem to show the same thing... a solid black line being traced on a map to the city of Ogburg followed by the disappearance of the city itself.
This adventure is best suited for heroes of levels 4 - 14 that like a bit closure.