- Main article: Sheogorath
Sheogorath has an old deal with Arch-Mage Shalidor in which the Vestige has to help Shalidor re-obtain all of his lorebooks that are not readable by Shalidor's own eyes do to a special enchantment that Sheogorath placed on the books out of entertainment.
This forces Shalidor to ask his assistant to translate the books for him at a slower pace. However, the books, little to Shalidor's knowledge were enchanted to drive his assistant "mad" resulting in a decision made by the Vestige at the end of the questline. The choice is a dozen Skyshards as a reward or a removal of the madness effect on the assistant, freeing her from her curse. If the choice is taking the Skyshards, Sheogorath will take the assistant with him back to the Shivering Isles.
A high-ranking member of the Mages Guild, Valaste wants the Vestige to perform a task for her. They must find a ruin nearby, which Valaste says may hold a store of ancient knowledge.
Valaste can't find anything in "Circus of Cheerful Slaughter" that tells her what the next of Sheogorath's trials is. She lets the Vestige try to read the book, and they are transported to Circus of Cheerful Slaughter.
In the final test, Sheogorath wants the Vestige to take a vacation in his family's chateau. However, all the three guest rooms are occupied, and two guests are cannibals. The correct guest is the one that isn't playing his role right and wants to get out. Next, the Vestige must find their way through a dark maze. Finally, they must fight their way through Madmen and Madwomen to a boss fight with Uncle Leo, a flesh atronach.
The Vestige and Shalidor journey to Eyevea, but Sheogorath left portals to Oblivion open and the island is covered in daedra. The Vestige fights Haskill. Sheogorath, who has been making Valaste slowly insane with his cursed books, offers to take her to the Shivering Isles. They can decide whether or not to save her.