DOCTOR: You destroyed a whole planet to save your own skin. You're insane.

BENNETT: The girl didn't know I'd been arrested. When we get back to Earth, she'd support my story. I dressed up as Koquillion to show her how terrible the people here were.

DOCTOR: If that happened, your guilt would have been hidden forever, hmm?

BENNETT: If it happened? Nothing's changed. There's only three more people for Koquillion to kill, that's all.