Nona the Ninth

It shouldn't be possible, after reading Gideon the Ninth and Harrow the Ninth, to finish another Locked Tomb novel and yet again be like "What the hell did I just read?!" However.

Nona the Ninth is yet another wonderful, unexpected, weird masterpiece from Tamsyn Muir.

Ok, confession time. I have given all the books in this series 5 stars without entirely being sure what is going on. I see this as a selling point, not a detraction.
Things become a little clearer in this book. A little.
At first it just seems a simple coming of age tale set in a dystopian city. However, the child concerned is a revenant of someone of great importance from the previous books (it's honestly not who you would think) and despite being adolescent has only actually been around for 6 months.
There is a fair bit of backstory reveal. It all started on Earth, slowly dying in the climate apocalypse and that sets the tone for all that comes after.
The prose is delivered in a style that always (to me) brings to mind REM lyrics, where the intent sometimes is to make meaning appear from random, unconnected snippets. This pulls you in hard as you try to figure out what is going on and the effort feels entirely worth it.
Apparently there is to be a fourth installment to wrap things up. The author is clear this is a case of the story running away from her. No complaints from me as I look forward to seeing the resolution of this.
Highly recommended if you are either invested in the series or prepared to start at the beginning. You can't just pick this one up and dive in.