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.
What's this? An itsy bitsy spider! How did you get in here? At least you can't spill all my secrets! Oh can't I? And enough with the itsy bitsy please WHAT?!? HOW?!? Y-Y-YOU can TALK?!? HOW can this BE??? Of course, you could just be having an hallucination  I could be I suppose... Oh no. My brother. He's poisoned me again, hasn't he?!? Well you got better last time, didn''t you? Eventually?  I suppose I did, didn't I? Then again... you could be some enchanted spy. One good way to find out! Hold still... Hey! I appreciate the National Enquirer as much as the next person but I prefer to read it before being splatted by it  Maybe you need a closer look! It is my scepter! And what is a National Enquirer??? You ARE a spy, AREN'T you??? Spill your guts or I'll squash them! I dodge you and now I am on the ceiling! That's right you dodge! Because I am the king! And only one of us is going to make it out of here alive. And it's not you!!! hahahahah! Ther are five different ways out of here. I can sneak under the doors 