There is no sign of anything to hold it in one position, you might assume it is a pull and release mechanism... if it still works.
There are some possibilities of what it could be that might be troubling.
Karthak:
Looking down the steps, there seems to be something deliberate in the spacing of the stone blocks at the base of the stairs. Switching from "Running Bond" to "Jack on Jack" when it would have been just as easy to stick with "Running Bond"... plus would like nicer.
Corum:
You get down the steps, and start to smell a complex smell. A sooty, burn scent with a bit of mildew and sewage.
On the lowest part of the angled roof above the steps, you see in charcoal scratches "Tunnel flooded" in undercommon.
" Tunnel flooded? Then they wouldn't be using this tunnel anymore... " Errik looks to the chain again, " A mechanism for draining the water? " he reaches out for the ring but then changes his mind and moves down the stairs to see for himself and causes a bit of confusion as he bumps into Corum " oup! My apologies... "
Errik examines the walls floor and roof for anything unusual as he goes, looking for anything that could give a clue to the chains purpose (also traps). Perception: 1d20 + 11 ⇒ (19) + 11 = 30
Karthak stares at the floor for as if transfixed, then he speaks:"Something's strange with those stone blocks down there" he whispers pointing at the blocks.
"Why choose those 2 different styles? I think the floor might be trapped somehow."
Karthak scoffs:"Bah! Let an expert do it! I just wanted to warn you before you went your merry way and triggered something!", he then proceeds to move near the floor and check the floor tiles
You all notice (Braxton notices after it is pointed out) a thin "scuff line" in the floor. Also, though the mortar between the bricks has eroded quite a bit, Errik notices the ceiling above where it is completely without mortar and a little wider of a gap... in line with the mark on the floor.
Errik:
From what you see in the ceiling and mark on the floor, This could be something that gets re-set by pulling the chain. There is also a bit of wear on the mortar and edges of the stone blocks on the wall there too, as if a panel the width of the hallway made most likely of metal, slides down. Could be just a way to block off the tunnel or could be part of a trap.
Karthak:
You are fairly certain you see a loose block in the floor just ahead which could be a pressure trigger.
" There in the ceiling, A panel that can drop down to block the tunnel... Or something more sinister, perhaps a guillotine. It looks like it could be reset with the chain. "
" Ah Karthak! Your a gem. a grumpy gem but a gem all the same! " Errik says with a wide smile. He then mutters an arcane sounding rhyme and with a small popping sound the pressure plate becomes bright red
Prestidigitation " Let's leave it alone for now, why would this tunnel be flooded? " he carefully moves forward to investigate. perception: 1d20 + 11 ⇒ (1) + 11 = 12
You make your way around the block marked red by Errik, and continue without seeing an end to the tunnel yet... by light or through darkvision. You do however soon hear the sound of water... just a little more than a trickle. The sooty mildewy scent increases as well... with a bit of a sewer smell as well.
Corum:
In addition to the trickle, you hear something a fair distance away which sounds like something moving through shallow water. About 150 feet past the pressure plate (a little more than 50 feet ahead of your current position) you see the ceiling slant down as if there are more steps down. There is something on the downward slanting ceiling that looks (from where you are now) like a small grate, but it is difficult to tell for certain what it is.
Corum rushes back and explains quickly, "In addition to the trickle, I hear something a fair distance away which sounds like something moving through shallow water. About 150 feet past the pressure plate I saw the ceiling slant down as if there are more steps down. There is something on the downward slanting ceiling that looked like a small grate, but it was difficult to tell for certain what it is. I am going back to investigate."
Corum returns to where he saw the grate, it appears (and when the rest of the group catches up with the light sources it is more clear) that there is some metal plate just behind the 5" x 3" grate. You also see the eight steps down as Corum pointed out.
you have now passed the area of your previous perception checks.
No the tunnel is open. There is a small rectangle of metal bars in the ceiling above the steps going down. The metal plate is just behind the metal bars.
Karthak finds another loose block in the steps down. As you step around it, you see another gap in the ceiling as before... with wear marks on the walls and floor... just at the base of the steps.
The tunnel continues past this for another 30 feet, then another set of steps down. Halfway down the next set of steps, the pale stone blocks of the walls and ceiling have crumbled away, and the tunnel appears to widen into a room.
You hear the trickle of water, and now hear the sound of movement through water.... and also now hear a brief sound of something dragging across gravel.
The air is moist and filthy here. This apparently has over time created a slightly slimy coating on the rock which starts right about where the grate is, and increases the closer you get to the opening ahead.
Braxton:
You see a path of footprints heading that direction which are little more than small smears with a different sheen to the untouched stone. Smallish human... maybe female human or male elf or humanish adolescent. (can roll knowledge roll to determine that if you care to)
The slime does not seem to be anything particularly remarkable. It just smells like a concentrated scent of what you have been smelling... smoky and mildewy.
The tracks do look like they are from an female half-elf.
Karthak stops and glances at the others, whispering back:"Are we good? Can we proceed? I wish to see for myself one of these creatures that you deem so worthy of fear. I pray they'll made a worthy offer for Gorum"
" looks like a half elf to me... Probably female from the size. I wonder what they are doing down here?"
He shakes his dagger to get rid of the slime and if the area is big enough he will draw his short bow.
You proceed and reach the end of the stone block walls and ceiling, exposing the dark rocky earth. This last set of stairs is narrower, and halfway down it opens up to a large room. The stairs appear to end in inches deep water.
You see rippling water, a dark earthen pillar... you can't get a sense of the dimensions of the room.
darkvision view from halfway down narrow stairs (just south of V,6))
You step down the stairs into murky several inchdeep water covering the broken floor. Just at the base of the steps are remnants of a stone floor that has since been shattered. The ceiling is high... maybe 30 feet. About twelve feet up, you see what is left of the previous ceiling (and floor for what was a room above) it is now just a jutting ring of rough rock. On top of the rocky pillars in this semi-flooded lower part are stone pillars of the top half of the opened-up room.
Just on the edge of Errik and Braxton's light, you see small but constant stream of water leaking from the ceiling into the water ahead. around (M-N,9-10)
Karthak clears his throat and speaks in a jolly tone:"People... I can see two ugly critters in front of us. I suggest you prepare yourself... we are going to have some fun!!"
Male Human(Tintalian) Alchemist(Beastmorph)-3/Drunken Brute (Barbarian)-2
I'll be staying in spot U5.
As he hears the hush tones the shady merchant tries to hide his reaction and palms one of his bombs just in case. All the sneakyness is broken when the dwarf bellows. "And I thought I didn't know subtly, dwarf's got me beat." He holds up his bomb, "Now be good childern come out and surrender to your Uncle Braxton and Dwarven McBigBlade over here. hehe."
As you move into the room, you see the heads of the two creatures submerge - just as the light starts to reach them. This makes it clear that the water is deeper towards the center of the room.
Further ahead in the darkness, you hear the voice of a young female.. "Help! Help me! They are going to hurt me!"
From what you saw of them, they looked like "slick-skinned" goblins. Being in the water as they are, there is a good chance they are some aquatic variant like grindylow... goblin torso, head, and arms... bottom half octopus-like tentacles.
Damnation! They are running away! Just a couple of aquatic goblins it would seem. I don't trust the waters but it seems we need to enter them if we want to deal with the creatures! But first let's see if I can soften them a tad"
Karthak drops his sword (free action) and shots a crossbow bolt towards the fleeing goblin in I12
Attack roll:1d20 + 5 ⇒ (2) + 5 = 7
Damage roll (if it hits):1d10 ⇒ 2