From the introduction:
At the bottom of a rocky slope in the hill country of Toth stretches a broad, rocky gorge, conspicuous in its near absence of trees and brush and for the large number of bones that jut from the dry, rocky soil. There, in that dying valley, legends tell of ancient ruins where a large black opal is said to lie, and of the strange creatures that dwell there. Welcome to Universal Adventures Adventure Module AO5 Bone Gorge.
Bone Gorge is the first part in a two-part adventure.