Against the Cult: Getting Away with It (1.8a)

@MaJunior - Theran can roll an INT (Investigation) check or a WIS (Perception) check, reflecting whether he is looking for expected clues (Investigation) or just trying to observe anything out of the ordinary (Perception).

Reptile calls down to the others about hearing the other Dungeon Busters. Still at the door, he hears more combat repartee:

Chase: "I don't want to have to kill you Donovan. Come to your senses."
Someone else: "Looks like you may the loser, Alan! Maybe you should follow the murderer's advice and run, huh?"
Another speaker: "You don't want to have to kill me?? I think you're misreading this situation. You are pretty good. It's a shame you didn't sleep long enough to get taken."
Yet another voice: "If you think I'm going to turn my back on these thugs, you're wrong. Something has taken hold of them, they're idiots, but they're still dangerous...I don't want to be responsible for the deaths of heroes!"

Looking more closely at the floor in the darkness, Theran considers: ::Why would a dirt clod be all the way over here? It could have been kicked, perhaps, but then it would have been in pieces. No, it's much more likely that it was caked to someone's boot and then it fell off as that person was walking around here.

::But why would someone be walking around here, in an empty corner?::

Theran feels the wall, and what his eyes can't see his fingers detect: there is a slight edge to the wall here: a part of the wall that juts out infinitesimally in a vertical line. It's either a bit of construction that was bricked in, or possibly a secret door! Theran begins probing and tapping along the wall around it, but doesn't immediately find a switch or pressure plate.

In examining, poking, and prodding around the join in the wall, the group discovers that one of the torch sconces is hinged. When it is pulled, it triggers a mechanism that causes the section of the eastern wall to slide back, revealing an unlit chamber beyond.