From the introduction:
The ziggurat is guarded by a huge sand serpent that hides below the surface and can swim in the sand like a fish in water. It will attack any non-serpent-people...
For 2nd level characters. This scenario is intended as an expansion of Blood for the Serpent King in DCC #082: Bride of the Black Manse (1st Printing), though it can function as a standalone adventure.