Heather Snow writes a wonderful mixture of popular science and strong female characters. In an era where females weren't suppose to have a brain and act as glorified chattel, Heather Snow's characters definitely break the mold without being total rebels.
What I love about this murder investigation/spy thriller is that Emma displays the traits of someone with Aspergers. Or at least a more mild form. Snow brilliantly weaves the behaviors into Emma and plausibly explaining her eccentricities within society at the time. We get both the benefits and drawbacks of her abilities. Granted, it's only a superficial treatment. The main focus is the murder investigation and the War Office investigation which are well intertwined.
Derick did annoy me a little. It's not his fault. I'm just getting jaded from reading all these tortured heroes or heroines which are traumatized and then can't seem to get over it for too many years. His personal demons with regards to his true heritage and his mother seemed to deeply effect him and was a constant shadow throughout the book. Yet all of a sudden with a magical explanation, it's all better now. Aside from that one pet peeve which isn't Snow's fault, I really enjoyed Derick and Emma's banter as well as their partnership.
I also loved Emma's many malapropisms. They were hysterical yet painful as they reflect her inability to grasp connotative language -- again like many high functioning autistic people.
I can't wait for the next installment coming out which deals with mental illness and PTSD during this period in history.