A Round Tunnel                                         NW     -      - 
(-------------------------------------------------)     - <---(M)---> E
                                                        -      S      -

You are walking through a small tunnel that leads deeper into Hellbent
Mountain.  The corridor curves gently to both sides, and you imagine that
you could follow it all the way around in a circle and end up back here
again.  The outer walls are made of a smooth black rock, but the interior
walls seem to glow with a dim red light.  There is another tunnel running
off to the northwest.