This episode was fantastically tense. I expected at least one of the side characters to get out alive, and each time another died I was surprised.

Speaking of the side characters, they were expertly written to cover the entire spectrum of likeability and garnered drastically different reactions when each one of them eventually died. I've never seen such a fantastic set of characters, from the lighthouse keeper who all clearly care for each other despite their differences, to a greedy capitalist doing whatever it take to get ahead, to a man just trying to save face.

I especially enjoyed how done Leela was with Adelaide's antics and how even the Doctor smiled when she threatened Palmerdale. I really like Leela so far.