Everybody stops and wonders how he knows that part of the story, and he admits he's run into similar-but-different pockets of Silurians before. They get all happy for a second, sweetly, but then the Doctor crushes their hopes by explaining that they were attacked and killed by humanity. I know sugarcoating's not his specialty, but come on. Find a better way. Of course, Restac is gloaty about that one, because it's just more context for what she already knows: Apes are truly a "vermin race." Even Nasreen is like, Nice one.
Ambrose comes downstairs -- now that Alaya has taken all three of her men away -- and threatens her with a taser unless she cures Mack. Alaya is, of course, delighted by this turn of events, because she's not a person, she's just a viewpoint, so the idea of getting tortured to death just to prove a point doesn't make the radical not-sense that it normally would. And again, Ambrose is being pretty rational: "First you take my son, now you hurt my dad. I'm just protecting my family here. That's all. I don't want to use it. I want you to put things right."
Which, maybe it's from being American, but that speech alone doesn't seem like a bad thing. If it were just this one Alaya and they had her tied up, you might offer to tase her if you thought it would help. But no, weapons are bad if you're a woman (but not if you're Mo), and interrogation is bad if you're a woman (but not if you're a lizard scientist man), so her completely rational train of thought is just indicative of how disgusting she really is.
Luckily we have Alaya, who makes no goddamn sense whatsoever, goading her into doing it: "Use it. Use it on me! You're too afraid! A woman who can't even protect her own child!" Ambrose finally tases the shit out of her -- once she's walked her lizard ass right up in Ambrose's face, note -- and then immediately apologizes at length, asking again for the cure for Mack. (Still not really doing anything wrong, considering how horrible Alaya is being.) "He's vermin! He deserves a painful death!" Ambrose begs her to stop being a bitch for like two seconds, but no, Alaya is not having it. She even points out that she called this one last week: "I knew it would be you! The one with the most to lose. The weakest!" At this point, Ambrose sort of loses it and kills her, but because neither of their characters make sense at all, it's up to the rest of the characters and the episode to explain to us how A) That all made sense and B) Ambrose is a bitch who deserves death.