Cassiopeia had a pile of books around her on the floor when the next book didn't come off the shelf. She tugged it again, but it was stuck firm. She stopped and looked at it from all angles, running her hand over the book and surrounding shelf. her fingers brushed over a small knot in the wood, releasing the top of the book and then releasing the mechanisms that held the shelf against the wall. The whole bookless section swung open silently, revealing a hallway that seemed to go on infinitely.