Trapped!

You grab the rope and pull it as hard as you can. It comes loose, but stops after a moment. You look up. The glass roof was rising. A small magnifying glass appeared from the wall suddenly and moved forward until it was even with the end of the rope. The sun's light was magnified, setting the tip alight. The rope slowly burned away, until, all of a sudden, a large explosion erupts from the wall. You fall back and hit your head on the far side, and are knocked unconscious.