Two and a half stars, but I don't mind rounding up. I was a little disappointed by the execution of what was a really intriguing, exciting premise. A twenty-first-century FBI agent hunting a nineteenth-century serial killer--it's time travel plus historical fiction plus mystery with a strong, smart female protagonist, and since I always feel like I should try more mysteries, I was actually quite excited by how much this appealed to me. 
 The writing fell short, though; it was canned, sounding like it came from the same template as every cheesy action movie. I hate how harsh it sounds, but truthfully, I felt like every sentence in this book was one I'd read somewhere else. In many cases, too, I had the distinct sense that McElwain was just excited to show off how much research she'd done, how much nineteenth-century slang she knew and how many ridiculous rules and habits of the time period she had learned. 
 I also don't think the dynamics of the time traveling were done well. I mean, who can't remember to stop using FBI jargon like "unsub" (unidentified subject) in front of people from a different century? These are words that even twenty-first-century civilians wouldn't understand. I liked Kendra and I loved her competence and skill at her job, but was confused by her totally inconsistent degrees of knowledge--particularly because her character is a genius with an eidetic memory. On page 160 she knows that since it's 1815, London won't have a true police force for another fourteen years, but on page 163 she doesn't know that in that time, only a prostitute would have gotten an abortion (something I--a non-genius with a worse-than-average memory--did know). On page 138 she knows all about subconjunctival and petechial hemorrhages, but on page 162 she's surprised to learn the incredibly obvious fact that a corpse's soft, uncalloused hands meant the person was not a servant. 
 The plot was good once it really got going, and though I never quite got over the pomposity of the dialogue, in the second half of the book I found myself excited every time I went to pick it back up. That's a big deal to me, given how skilled my anxiety is at making even something I really want to read feel stressful and laborious. This book should have been a lot less than 497 pages, but the fact that I read it so quickly redeems it a bit on that count (although to be fair, I skimmed some fairly large sections in the middle). 
 I also liked several short conversations that happened throughout the book. A woman going back two hundred years presents some obvious opportunities for thinking about humanity, civilization, and human nature, and I appreciated Kendra's (or maybe McElwain's) thoughts on the subject. 
 "Times have changed, Miss Donovan. Mankind has evolved. We are more enlightened thinkers than our ancestors." 
 "I've heard that before." 
 He raised his brows. "You don't believe we are evolving as a species?" 
 She thought of her earlier epiphany, that she wasn't superior to her nineteenth-century compatriots. And she thought of the countless murder boards she'd stood before, centuries from now, detailing man's depravity toward man, and shook her head. "We might be becoming more civilized as a whole--and I'm not even sure about that--but I don't think mankind ever really changes. We're not smarter, better, kinder people, Doctor." She paused, grim. "We're just inventing better technology." 
 I can't pretend to think any more optimistically than she does. 
 About the identity of the murderer: (view spoiler)[It was a tad underwhelming. We knew it had to be one of the three, but none of them were ever developed enough that it really mattered when we found out which it was. Thomas's and Gabriel's roles were the most surprising part of the whole thing, and they were over too quickly. (hide spoiler)] 
 I liked this one well enough, but the Goodreads description of book two told me all I needed to know about it, so I probably won't be continuing the series. Although I can also see myself picking up book three when it comes out, just to see where things went. I'll cross that bridge when I come to it.