This felt like two books in one. There was an enormously complicated backstory, all about Edouard Villet's trial and his foster son Nicholas's response to his wrongful execution, which led him to vow revenge upon Count Montesq, creating in the process the persona of the thief Donatien, which put him in direct conflict with the Sherlock Holmes and Dr Watson of Ile-Rien (called Sebastien Ronsard and Dr Hall here), such that they develop a years-long rivalry, each trying to outwit the other as both pursue Montesq for their own purposes. That's a book in itself right there! But then we build on top of that a mysterious necromancer who gets in the way of Nicholas's plot to overthrow Montesq, and then there are housefuls of dead bodies and impertinent golems and stone gargoyles coming to life and the whole situation is interfering in Nicholas's schemes most inconveniently--and then Ronsard turns out to be interested in things, and then there are sewers and catacombs and all sorts of hijinks ensue, which turn out to be related to Edouard's wrongful death in quite complex and rather elegant ways. 

Martha Wells is very good at keeping this massive, stuffed beast of a plot ticking along smoothly, but I must confess that I found it dragged at times. There was so much plot that the overall trajectory of events just moved slowly. As much as I enjoy charades and confidence games and house-breaking and sneaking and disguises, I did eventually start losing the thread a bit. 

There's also a token girl. But just the one.