You step through the doorframe, your eyes barely having time to adjust to the dimness before the door slams shut behind you. For a few terrifying moments, you experience a total loss of spatial awareness. Then, gradually, your vision adjusts to the darkness.

You find yourself in a long, wide corridor. Moonlight filters through windows on both sides, but you can't make out the outside surroundings. Suddenly you heard rustling sounds ahead, further down the dark corridor..