A Two-Round Living Greyhawk Bone March Regional Adventure
From the introduction:
A paladin runs for his life and stumbles across a group of adventurers. The poor man is badly wounded and in a state of shock, screaming about a mysterious tower and very dangerous opponents. Can this be true, or it is the raving of a young man on the verge of insanity? Do the adventurers have what it takes to check out for themselves the horrors of this mysterious building?