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
spider
king
I am a king of the whole empire. I give rules and pursuit them. I am brave and fearless.
Such a long day today, now I have to go into my secret tunel to meet with an informant. Why are you meeting in this secret tunnel? What was that!? A talking spider!!! Yes I am because you're in a magical tunnel I've owned it this entire time and I did not know it was magical? Well what do you know spider? i know something that you don't know. I am actually the owner of this tunnel How does a spider own a tunnel? Did I drink too much at the banquet? Oh dear, I am actually your long lost mother. I was cursed by your father. My Mother! But father has been dead for years, how do I break the curse?  You have to bring me out of this tunnel and buy me a diamond ring. There are many diamond rings, I have to buy one? That is a really strange curse. You have to find the diamond ring that your father gave to me. It has his name on it.