Once the last prisoner shuffles in, the mighty doors close with a loud clang. For a few moments, all is dark.
Then, the torches flicker to life
One by one the walls begin to light up, the sticks on the walls burning without being consumed. Magic torches. Now that they can see the room properly, they find themselves in a long corridor, the middle of which is made up of a bridge. Below said bridge is a sinkhole in the sand, waiting for someone to accidentally fall in.