The party has followed the southern tunnel for some distance, only to come
to a dead end in the form of a cave-in.  From the rubble which fills the
30'-wide passage, a pale-blue hand protrudes. 

Ozzy:  Hmm.... (he walks up to examine the hand) 'Wonder what kinda   
  critter  this was...
Tasencia:  Hmmmmm....  It might all begin to make sense now.  If that   
  buried creature has the look of a kobold or goblin and has a big head, I   
  may know what things are like around here, including those rat men.  But 
  I will wait to see if my assumption is true before I explain.
Autumn:  If you can explain the rat things, I'd love to hear about it.
Rimli:  Well, le's dig 'im out, then. (he and Ozzy begin to clear away some
  of the rubble around the hand in hopes of finding the rest of the body)

The two uncover a badly-smashed body, about 4' tall (when he was standing,
that is) and dressed in familiar leather armor.  Equally familiar are his
dagger and pole-arm. 

Rimli:  Och!  'S a bloody derro!
Tasencia:  (as her theory flies out the window) Oh.  Never mind.
Alenniel:  I thought this was where they came from.  What did they do, 
  collapse the tunnel after themselves?
Ajax:  (looking at the huge mass of rubble) I don't like this.  There's
  too much collapsing going on in these caves.  
Autumn:  (looks around) How stable do you think these tunnels we're   
  walking in are?
Rimli:  These 'ere?  Wha'ever dug these out didna ken much abou' wha' they
  were doin'.  Th' earth 'ere's too loose an' soft for a wide passage like
  this one. (as if to demonstrate, he pounds his fist against the tunnel
  wall, causing a few bits of dirt and rock to fall from the ceiling) See?
Greythur:  Are we in danger here?
Rimli:  Nah.  Th' cave-in 'ere took care o' most of it.  Th' thin' is, derro dig
  bet'er than this mess.  This shouldna 'appened, with them diggin'.
Autumn:  (shudders) Maybe they had their slaves do it....
Alenniel:  Well, should we try to dig through or should we go back?
Autumn:  Dig through?  I say let the human slave-takers stay on the other
  side of this dirt, thank you very much.
Rimli:  'Sides, we don' 'ave th' tools t' dig this out right.  
Ajax:  Let's just go back.  (he looks up at the ceiling) I still don't trust 
  this tunnel not to come down on top of me.

Deciding to leave this cave-in alone for now, you return to the
corpse-filled cavern and try the other two exits.  The first leads
northwest to what looks like a naturally-formed cave about twenty or
thirty feet across and thirty or so feet long, with no other exits.  It is
completely empty apart from an acrid odor-- the same one you smelled in
the first cavern.  The second tunnel from the Cavern o' Corpses heads
northeast for thirty feet, then splits.  One tunnel goes north, and
another turns southeast. 

Autumn:  (to Tasencia) So, no explanation for the rat-men?
Tasencia:  Not at present, no.
Autumn:  Well, keep me posted.