Lit only by scattered torches, The dungeon lies far underneath the castle.  Bandits and Thieves who find themselves there are met with cold stone walls and floors, with chains and bars restricting movement.  Guards patrol the corridors, keeping an eye out for any escape attempt or misdeed.  The only comforts afforded in the Dungeon are the piles of hay for sleeping.
Dungeon, Inside Castle
thief
guard
I am a king's guard in the royal palace. I am fighting against the army trying to overthrow the king. I am a guard who has pledge my life to defend the king.
I have seen you before! Thief what is it you think you will get today? I am not here to thieve today...I am here to see my brother who is being held here. Is he a thief too? Yes sir...he did thieve but I'm trying to convince him to tell on another thief so he can get out sooner...you know...make a deal. A deal? What is it you have in mind? He knows the name of the person who stole a jewel from the castle...that should be worth something...right? It should be! Convince him! I'll need some time with him...guard...man it stinks in here...doesn't anyone muck this place out? I will just wait and listen around the corner! Do not try anything! I guess you'll be wanting to hold onto this? I'll keep that! Now get convincing! He says it was Duke SoinSo who stole the jewel... my brother was there...yes...but just to get a loaf of bread...he overheard the Duke and the queen herself talking about taking the jewel...The queen is out to hurt the King!!!