From the introduction:
The adventurers are trekking across a desert of powdered bone in a level of the underworld so deep that it is part of the land of the dead, a place known as the White Desert. The party is on a mission to recover a legendary gem that has fallen, in a meteorite, into the lowest levels of the underworld and seem to be on the right track.
The adventurers, covered with bone powder, enter a region of mists, where the air is as white as the powdered bone beneath their feet.
For 3rd level characters.