I was blissfully ignorant of a book, usually translated into Human languages as The Gospels of Satan, until it was stolen from the Great Library.

My twin sister, a Senior Scholar, showed up at my door and asked me to help her retrieve the cursed book. It's magical, priceless, and in the wrong hands might be dangerous.

It could be anywhere in thousands of Worlds, but the logical place for the thieves to sell it is the Great Marketplace at the Crossroads of the Worlds. Not out in the open, but in the shadows known as the Night Market, where the buyers and sellers don't mind disposing of a body or two.