From the frontpage of the module:
The primordial force known as The Serpent grows stronger, longing to regain the power it lost to the gods at the beginning of time. At the center of its plans are a young Flan girl, preternaturally gifted in the arcane arts; an honorable kobold following his destiny; and a group of adventurers willing to brave the infernal wastes to end the threat. A combat-intensive, one-round Core adventure set in the Burneal Forest, Greyghawk City, and the plane of AVernus for characters level 9 - 15 (APLs 10 - 14). This is the final adventure in the Windows to the Serpent's Soul series, comprising COR4-01 Shedding Scales, COR5-07 Clipping Wings, and COR6-08 Catching Breath.