Our remaining heroes-- Jarmangle, Tralamin, Feer, Robyn, and Irving-- blockade the fort's entrance and reinstall a couple of traps they had disarmed. The zombie gnolls rush in and, after a long and tense battle, they are defeated and the curse on the fort lifted. Exhausted, our heroes make camp for the night.
As they slumber, they each of them have a strange dream, which imparts to each a different, cryptic message. (Tralamin, who does not sleep, recieves his message jumbled-up during his meditations.) Our heroes share their experiences with one another, but cannot quite make sense of it.
Come morning, they head for the coral palace in the dried up lake just southwest of the fort. They discover that, when the lake was filled with water, it served as a prison for the most notorious of mermen.
They learn that merman culture prizes mathematics above all else-- for them it is magic, religion, culture, and law. Mermen are also biologically immortal-- the gift of Seldak, who is also considered their greatest criminal because he solved "the forbidden proof". There are several towers that, in the past, one could have swimmed up. Irving possesses Feer's battleferret, and uses his magehand to float himself up the various towers, taking note of the corpses of the various mer-criminals, who died without water to breathe.
One tower, which houses Seldak, is inaccessible: a door, armed with powerful and deadly magic, blocks its path. But examining the door, our heroes soon realize that their strange dreams provided each of them with a key to the puzzle. Putting their information together, they are able to open the door without incurring its wrath.
The tower on the other side is still filled with water; indeed, the water does not rush out of now-opened door but stays there by some strange sort of magic. Jarmangle swims up the tower, but runs afoul of several explosive balls that were placed there decades ago. His life is saved thanks to the intervention of Seldak-- still alive, and desperate for vengeance against the mermen who branded him a heretic.
Jarmangle is quickly dominated by the psionic merman, and Tralamin seems eager to help him achieve his goal, much to Irving's chagrin. The wizard is hesitant to interfere in the mermen's affairs, but he, Feer, and Robyn decide that it is best to stop him.
Seldak, infuriated, uses his forbidden proof to create living beings out of thin air, and battle is soon joined. He proves a formidable opponent, opening portals to redirect their attacks and place himself out of harm's way. He manages to escape, using linked portals and his personal water-bubble.
During the battle, the floor collapses, revealing a sprawling ancient dungeon beneath the prison. It will, however, have to wait; they must stop Seldak!