I don't see how a torch in a D&D setting is intriguing, but hey, whatever.
You scrape Raven Razor against a rock. The sparks light the torch ablaze, along with part of the wall. You quickly step back to keep from being burned.
You look around you.
Looking up you see a faint glimmer of red, what must be Arachnea. Good thing she can't see you from up there.
You find a small storm drain leading under the walls.
Now what?