Based on the Advanced Dungeons & Dragons adventure Lost Caverns of Tsojcanth by Gary Gygax, Lost Caverns is and adventure module for characters level 6-10.
From the publishers website:
"Nearly a century ago, the Arch-Magess Izzlshyzl tasked her evil minions to enslave the lands around her home. The successful conquest brought about the subjugation of the lands around her realm for a decade. Captured treasure poured into the mage's coffers though never sufficient to quench her insatiable demands for jewelry and luxury goods. According to legend, a discovery deep within the mountains caused her prestige to soar when magic of unsurpassed power saw the light of day. It is certain the Arch-Magess ruled her dominion from the caverns where she conducted arcane experiments and rituals in order to further increase her already formidible magical powers. Her success and increasing prowess ironically proved to be her downfall."