The Doctor: When you took your vows, did you agree to this?
Novice Hame: The Sisterhood had sworn to help.
The Doctor: What? By killing?
Novice Hame: They're not real people. They're specially grown. They have no proper existence.
The Doctor: What's the turnover, hmmm? Thousand a day? Thousand the next? Thousand the next? How many thousand? For how many years? How many?!?