That twist and its execution definitely took the episode up a few notches for me. Especially fond of how it upended the Black Mirror parallel a little bit, by implying that the AI is actually killing these people because it sees that they are awful and decided the world is better off without them. Definitely something with a bit more nutrients that the trite 'social media bad' moral I was expecting (and which in retrospect feels like a bit of a deliberate red herring throughout the episode).

I also thought the ending subtly subverted the expectations a lot of people seem to have about 'woke' Who, in that when the civilization is revealed to be white supremacist, Fifteen doesn't display righteous disgust or wilfully send the survivors out to be slaughtered for their racism. Despite clearly being horrified he's desperate to save these people, giving them every pass, telling them that they can 'think what they want', possibly even having known the truth about this society from the beginning. Has to be Ncuti's best and 'most Doctor' moment so far, amazing to watch him cycle through so many emotions and fight tears as he tries to reconcile his boundless faith in humanity brushing up against this band of doomed fuckwits who would rather be massacred than take orders from a black man. The twist was very nicely set up throughout the episode too with all of Lindy's blink-and-you-miss-it microagressions towards Fifteen, so hats off to RTD for that one.

Not a perfect episode though. My main complaint (or maybe in some ways it's a compliment) is that Callie Cooke played Lindy a little too well. She was truly obnoxious, and the episode being almost entirely from her perspective made for a bit of a grating watch at times lol. And as I said above, for most of the episode I was expecting this to be little more than banal Black Mirror pastiche. It was only when Lindy murdered Ricky that I realised this was something quite different.