You head south, and the corridor just continues to stretch on and on. As you come close to where the northwest corner of the throne room is next to the corridor, you hear some clanging, the sound of machinery and chains moving, and then silence. You can see in the distance that the hallway turns left (east) and that there is daylight indirectly lighting the corner. You then see someone come out of a doorway in the hall, with their backs to you (lucky they didn’t see your torches), and they head east down the corridor towards the daylight.
You continue on cautiously and as silently as you can, until you are standing next to a door in the west wall. The door that you saw the person come out of is still 20 feet away, just barely beyond the corner.
As you stand there silently, you hear voices echoing around the corner, and you recognize the voice of the Ubue leader you met in the throne room earlier. “Pluton/Mari/Saam, are you ok?”
Another female voice, presumably Mari says, “Saam again! He loves looking outside, going to kill us! Damn Jupiter Blood Sucker snuck up on us, Pluton head got it this time. Fought it off and had to drink from fountain.”
There is a chorus of laughter from the other Ubues. The leader says, “Saam, you earned your trio watch duty! Stay and guard door, nap time for the rest of us!” You hear footsteps walking away, then a door open and close.
What follows is a bit of minor bickering between Pluton/Mari/Saam, the outcome is that Pluton and Mari insist they get to nap too, so Saam gets to stay awake and watch the door.
The green arrows show the locations of the two doors in the hallway. (edited)