Knowing the Unknowable. short to medium
A Guvner scholar studying the every swirling chaos of Limbo recently made a historic discovery. He found a book that explains how the apparent chaos of the plane is actually extremely complex applications of universal laws. The Fraternity of Order rejoices at this news and sends a team to retrieve the scholars research. Unfortunately, the Scholar has gone completely barmy. The Chaosmen don't believe a word of this screed and assume that the book is a powerful artifact of chaos. Both factions want the book (the Guvners to study it and the Chaosmen to spread chaos). Of course the Harmonium is concerned about what this item could do so it has to get involved.
The PC's could be members of any of the above factions, or they could be sent by other factions to retrieve, destroy or investigate the book. Members of the Bleak Cabal could seek out the Scholar to insure his new condition is treated (if they can work up the motivation that is).
I'm Modron, but that is allright. medium to long
Barmy girl has escaped from Gatehouse and Bleakers need help to find her before she gets hurt. Girl has unusual personality disorder: she think she is modron, and what is more unusual she has strange effect on other modrons (even rouge ones). Each modron that girl meets regards (and obeys) her as its superior. Things gets complicated when power hungry Guverner learns about her "ability" and wants to conduct interesting experiment: he wants to test if primus will obey the orders of "little modron girl".
One-eyed, one-horned, flying, purple people eater says: "Monsters are nature's way for keeping XPs fresh."