Oh, ok. Now I see. You're gonna need the Lens of Truth to find it. There is a passage hidden on the ground that you need to bomb. It's in the top left corner of a room. I think it's the room with the Leever. Same secret on the opposite side of the "horse shoe". lol
Let me know if this helps
Edited by AtrusW0nder, 30 January 2014 - 07:52 PM.