I’ve had Middlegame on my TBR shelf about since it came out and I’m just now getting to it. I think it really did help me to have read several other things by Seanan McGuire, and also to know that she considers this her most technical work to date. There are several parallel stories set up as well as some time bending woven into the story, and for me it mostly works.
The main plotline is that of Roger and Dodger, twins created by mostly evil alchemist James Reed in order to bring the fundamental principles of the world, The Doctrine of Ethos, into physical being. The story follows them growing up apart, developing strange abilities, and finding and losing each other, all the while managing to stay alive and avoid being murdered or killed by various means and individuals. Reed’s mentor, whom he loved and later killed, came up with the main idea but the organizations governing alchemy refused to accept her ideas, so she basically went underground until she was killed by Reed. Roger and Dodger are not the only participants in Reed’s experiments though, they’re just the pair who manage to survive. Erin is half of a previous attempt of a similar experiment whose other half was killed, and she’s an interestingly ambiguous character in terms of whose side she’s on for much of the story.
The whole point of bringing The Doctrine into being is to get on the Improbable Road and get to the Impossible City, vaguely defined and understood alchemical planes of existence (I think). Reed seems to think that if he can use Roger and Dodger to achieve this, he will basically be able to control the world. Something about Roger and Dodger seems to be able to control time for most of the novel which is recorded by an astrolabe left behind by Asphodel, Reed’s mentor and creator. Their goal becomes trying to figure out what they are, then how to use their abilities to stop Reed, and set their world right. The other thing Asphodel left behind was a series of stories Over the Woodward Wall, which seems to be a combination of the Oz stories by Baum (who apparently wrote them to compete with Asphodel) and Alice in Wonderland. The stories were published to ingrain certain alchemical principles in the next generation to maybe make them more receptive to the author’s ways of thinking. Excerpts from the stories are scattered throughout the novel, and direct references are made to them by various characters.
There’s a lot in the novel; lots of story, character, and world. Some of it sometimes is not as detailed as I’d like, such as the Impossible City which is pretty important given that it’s the reason for most everything that happens. On the one hand, since no one seems to quite understand it, it makes sense there wouldn’t be much detail. But on the other, it’s sometimes hard to find something important when there’s virtually no information about it. Not even much theory, and there’s some theory about other things, so why not this?