The light from her sonic dims, and the Doctor is left in the dark, frozen and panicked. Three knocks. He only heard three knocks, so he's not in trouble, but Morgana could be.

"Morgana!" he cries out, fear seizing him. Should he look for her? Where could she have gone?

He grips the side of the bookshelf and gives it a tug. Most of the books are gone, but it's firmly attached to the wall.

"Oh, no."