Ghoul Island: Clean Up Crew

While, they may have won the day in Act 2, Act 3 continues the battle to remove the Cult of Ghatanothoa from their Citadel. 

The characters find a wealth of knowledge, a trapped being of malevolent intent, and an icon to Ghatanothoa’s progenitor, the great Cthulhu. With each revelation, the sense of dread grows, and the characters begin to fear that they have underestimated the power of the Cult. Their worst fears are confirmed when they encounter the seat of Ghatanothoa’s power—its Elder Influence.

After a failed initial attempt, the characters must retreat and regroup for the final confrontation in Act 4 of this epic saga.

Certain spells and monsters in this adventure come from Sandy Petersen's Cthulhu Mythos.  While it is possible to play the adventure without that material, some adjustment will be required.  SPCM also contains the core mechanics of a Cthulhu Mythos game, including special skills, languages, races, and classes, rules for Dread and Insanity, and a full bestiary.  It's very much recommended, to get full enjoyment out of any Cthulhu Mythos adventure.