DOCTOR: Displacing someone back in time creates time energy, and that is what the Angels feed on. But normally, it's a one off, a hit and run. If they could keep hold of their victims, feed off their time energy over and over again. This place is a farm. A battery farm. How many Angels in New York?

RIVER: It's like they've taken over every statue in the city.

DOCTOR: The Angels take Manhattan because they can, because they've never had a food source like this one. The city that never sleeps.