A Dark Tunnel                                          -      N      - 
(-------------------------------------------------)     - <---(M)---> E
                                                        -      -      -

This narrow corridor runs out of a large chamber, and it is so small that
behind you, and you becoming increasingly sure that the strange noises that
meet your ears are the sound of something creeping along after you.  You
quicken your pace in an attempt to reach a more open area.