DOCTOR: Clara, why don't I have a radio in the TARDIS?

CLARA: You took it apart and used the pieces to make a clockwork squirrel.

BENNETT: Wait, you're going to go back in time? How do you do that?

DOCTOR: Extremely well.

DOCTOR: It's just what I was saying. You live and you die. That's it. The ghosts are aberrations. A splinter of time in the skin. They're unnatural. She wants to get away from them.

CLARA: So, what do we do?

(The Doctor turns a handle on the console. The Cloister Bell stops and the engines power down.)

DOCTOR: Put the handbrake on.