Underground 4

I forced myself to stay calm; everything was dark and and silent. Some time later, I saw a light in the end of the corridor. The light came from a grill in the ceiling. It looked like an air duct. It was obvious I couldn´t escape through it, though. As a result of the light, I was able to see a door just beside me, however. An old, rusty metal door. It seemed nobody had used it for a long time. I threw the door open and discovered something I did not expect.