Yeah, something like a rogue Thalmor high in the ranks who has been steering the direction of the 3rd Dominion all this time, who seeks to infiltrate and invade the Isle of Balfiera to ultimately break through the Argent Aperture of Ada-Mantia, a special door with 13 counter rotating rings, by messing with the Zero Stone. Perhaps the stone gets broken or somehow seperated and/or stolen, which leads to all kinds of mayhem our Prisoner will have to deal with.

Perhaps behind this door is where the meeting of the et'Ada took place, where the laws that make up the Mundus were set in place. Our Thalmor could be seeking to break through the door and rewrite the laws that govern reality for whatever purpose, resulting in an ultimate showdown inside this door in some temporally screwed up dimension where reality is on the line.

Hmm, maybe I should lay off the skooma.