Simplicity

"Well, we were both in the same cell, and before we both went to sleep. We notice some sorta switch on our wall, and (of course) we decided to flip it, and it opened a path through the brick wall, and led underground. We though it was a way out, followed it down here and we lost our way going down and... Well I'm sure you know the rest."

Well it seems they got here the same way you did. You wonder if this is some set up for you to escape.