Centuries after the Catastrophe that made living on the surface of Earth too dangerous for most humans, Recoletta is a thriving underground city. Conditions have improved on the surface enough so that there are farming communities up there, but the vast majority of people would rather stay safe, thank you. 
 Inspector Liesl Malone of the Recoletta Municipal police force is one of the people keeping them safe. She's just finishing up a long case involving explosives smugglers when Malone is alerted to a murder. It happened over in the wealthy part of town, so needs delicate handling. The inspector is surprised to learn that the victim is a historian, and disturbed to find that whatever he was working on at the time of his murder was stolen. 
 Across town, Jane Lin is a specialty laundress for the well-to-do, hand-washing and mending the clothing and other fabric items the Whitenails (so called because they don't have to do manual labor and can wear their fingernails long) can't trust to ordinary servants. Her best friend, reporter Fredrick Anders, informs Jane of the murder, but it has nothing to do with her. Until, that is, a missing button enmeshes her in the case. 
 Recoletta is a city of secrets, especially as the Council has forbidden civilians from studying "antebellum" (apparently the Catastrophe was at least partially a war) history, and also banned various kinds of literature deemed unsuitable for the current civilization. Malone and her rookie partner Rafe Sundar find themselves stonewalled by the Directorate of Preservation, which has the monopoly on historical research, even as the death toll mounts. 
 Jane Lin, meanwhile, keeps stumbling on clues and finds herself becoming attracted to the suave and darkly handsome Roman Arnault, who has an unsavory reputation and may or may not have anything to do with the murders. After all, not all dark deeds are connected. But many are. 
 The setting has a vaguely Victorian feel, with gaslight and frequent orphanings. The title comes from a poem by Matthew Arnold. But this isn't steampunk as such, and the author doesn't feel compelled to stick to one era for inspiration. 
 In the end, this book is more political thriller than mystery, with an ending that upsets the status quo and paves the way for a sequel or two. 
 One of the things I really like about this book is that the underground cities are not completely isolated from the outside world. You can go to the surface any time you want, visit farms and other cities, there's even immigration! The hermetically sealed civilization has been overdone in science fiction. 
 A jarring note for me was the infodump characters used at one point in the narrative. They have names that are too referential to be a coincidence, and feel like the author is just trying to be cute. 
 Overall, a solid effort that I would recommend to the intersection of science fiction and political thriller fans.