This is a dungeon crawl designed for a single evening of Dungeons & Dragons.
 
As recorded history is concerned, there has always been a strange void in the night sky; a circular area curiously absent of any stars. The myth goes that there was a moon, but Selune stole it away, to give to another world on another plane. All that remains now is its shadow.
 
There is the well-known regional legend of Iptiz, a spirit naga whose greed was remarkable even among its own kind. Murderous raids and relentless pillaging yielded a hoard so valuable that the creature needed some place to store and protect it. Thus was the Vault conceived: an underground complex custom built to destroy anyone who is not its creator. Years ago, Iptiz's campaign of terror suddenly ended without precursor or cause. The location of the Vault was never discovered.
 
Until now. The ring-city of Sulindal, built upon the shores of a mile-wide desert oasis, has come under martial law by an invading army of yuan-ti. They intend to exploit the resources in this renowned city of knowledge to locate the third and final Beacon of Selune. Their ultimate motive is to activate the beacons and restore the missing moon, which will cataclysmically alter the tidal forces of a nearby ocean and flood the entire desert.