From the back cover:
"You stand before a great throne of lapis lazuli. The massive chamber is also blue, even the air has an indigo quality, perhaps from the strangely convoluted coils of smoke rising from the braziers of azure metal. Encompassed by the great chair is a man whose presence inspires awe, Tenser the Archmage.
High above the City of Greyhawk, somewhere upon the lonely south coast of the Nyr Dyv, you and your associates trekked to answer a summons that could not be taken lightly. You are about to begin a quest to a mysterious island where lies the fabled Crook of Rao. Only the bravest can face the isle's obscure jungles, its most fearsome monsters, and its ultimate secret. Can you survive where even the mighty followers of Tenser have failed?
Isle of the Ape is a challenging adventure for high-level play. This adventure, designed for the WORLD OF GREYHAWK Campaign, is for use with Unearthed Arcana.
An Adventure for Character Levels 18 and up."