Mortal Engines was like the YA book series with the best politics. Maybe it was tied with A Series of Unfortunate Events, but those books didn’t go too hard with praxis. These were books that were fervently anti-capitalist and anti-nationalist, written from a clearly defined Anarcho-Communist perspective. Sure, the conceit of autonomous, mobile city states is maybe a big hurdle to overcome — but to reflect a societal condition as fucked as late-capitalism takes some doing.
So I pretty much love the Mortal Engines books; have since I was a kid. They are a sorta class-conscious, post-apocalyptic version of steampunk that you don’t see too often. Steampunk as a genre often gets too trapped in the ‘Steam’ to really pay attention to the ‘Punk’.