The Locked Tomb Trilogy by Tamsyn Muir continues with Harrow the Ninth. This takes place shortly after the events of Gideon the Ninth and quickly starts tackling some of the loose ends left from that book, all while introducing new things to be excited about. Combining science fiction, fantasy, horror, and who knows what else, this book will surprise you.
Read on for my spoiler-free review, but bear in mind that, as a sequel, I consider events from the prior novel fair game.