With Orrick Nightglider dropping two sets of keys on one key-ring, we are to assume the bone key releases Lieutenant Culpepper. Therefore the hieroglyphic key is still missing a lock somewhere. Hieroglyphics are synonymous with ancient Egypt, so it is a safe bet to assume that the hieroglyphic key has something to do with that "next step." What exactly does the key covered in hieroglyphics unlock?
Well the most famous theory seems to be another cheating dungeon located somewhere in Krokotopia; it just hasn't been revealed to us yet. The Spiral Geographic Society Warehouse is located in Marleybone and is associated with the Celestia storyline. The Waterworks is located in Crab Alley and is loosely affiliated with the storyline there. The Tower of the Helephant is not associated with any current storyline (unless you count how Headmistress knows about the Heart of the Helephant), but does allude to a possible side story involving the world of Yago. So a future world certainly has a background story to help lay the foundation.
What about the last mystery? Krokotopia is the next step to what? The Spiral is made of many different worlds, so how can something be coming to the Spiral? Is there more than one Spiral out there? It clearly isn't Morganthe, she is from Avalon/Zafaria which is in our Spiral. It would seem there is a greater evil out there beyond Morganthe....beyond our Spiral. But what will cause it to come to our Spiral?
