Detroit Breakdown is a historical mystery set exactly 100 years in our past. The city is Detroit, naturally, but a big portion of the novel is set in Eloise, a sanitarium or, less politely, an insane asylum. Inside the asylum there's a serial killer who's patterning the murders on those in The Phantom of the Opera.
The story is told in alternating first-person sections by Will Anderson and Elizabeth Hume, who have considerable history from the first two volumes of this series. Don't worry if you haven't read the others. I hadn't, and I found that history adroitly filled in as the novel progressed.
Elizabeth has a special interest in stopping the murders because one of the inmates at Eloise is her brother. Will comes up with the idea of having himself committed to the sanitarium to investigate from the inside. As you probably know, that never seems to work out so well.
The horrors of the asylum are depicted very well, and some of the "cures" Will is subjected to are frightening. Elizabeth turns out to be as kick-ass as you could hope for, and Detroit Breakdown turns out to be a fast-moving and entertaining book.