"Silence in the Library"

No spoilers, I promise. Just wanted to say that Steven Moffatt managed to fit more ideas, world-building, character development, plot, and genuine scares into half a story than the rest of this season of Doctor Who combined. He has such a skill for teasing iconic images--zombie kids with gas-mask faces, murderous statues, and now shadows--out of clever SFnal ideas, thereby pleasing both sides of my brain while blowing it at the same time. I'm sure those qualities will bleed into the show as a whole, once he's producer. The sooner he takes over, the better.

Imho, of course.