this secret tunnel is like a vein to the castle.  It leads to many other rooms within the castle.  This includes passage to the dungeon, the throne room, the kings chambers, and a secret exit to the outside.  You must be careful because the tunnel is small to maintain its secrecy.  There are 5 different rooms to the castle that can be accessed through this room. This also proves as a good escape route as enemies with large armor will not be able to fit through.
Secret Tunnel, Inside Castle
king
spider
I am a spider. I am large, black, and have eight hairy legs. I wait to trap insects in my web. I enjoy eating unwary prey. I live in a darkened wood near a remote village.
hello I knew I would find you here, did you get that information you talked to me about? i didnt....it was kept more securely Kept securly, you are suppose to evesdrop, did you go or not? well, your highness, i tried my best really You will have to try again, that is all there is to it. Let me get going then I can't beleive you didn't get the information, the kingdom rides on this spider! I am really sorry for my incompetence You are an insect I suppose, do this right and I will bring you that faery you wanted the other day. i will get it right this time You better, I don't know what all this hugging is about. 