Wow. I really enjoyed the first book and the second one was a disappointment compared to that. I think Thomas tried to bite off more than could be reasonably followed in this book. Maybe some of it could have been pushed to a third book. Having Charlotte Holmes and Mrs. Watson taking on cases, having Charlotte solving ciphers for Lord Bancroft, and the follow-up to Moriarty and the half-brother we heard about in the last book all thrown together didn't make for an engaging read. Don't even get me started on Inspector Treadles and his nonsense about women. The man goes around ticked that the brilliant Sherlock Holmes is Charlotte Holmes. And then is even more unhappy when his wife admits she wishes she could run her father's business.
After the events in book #1, Charlotte and Mrs. Watson are still doing their detective business as Sherlock Holmes. However, things become awkward when Lord Ingram's wife comes asking for help in finding her first love. There's a lot of hand-waving away why Charlotte agrees to work on this case, but ultimately that case leads to a larger mystery that I didn't think was put together very well.
Charlotte is still quite good at deducting. But you do read a lot about what she eats, her tea, and how hungry she is at all times. Why Thomas switched Holmes addiction to Charlotte being an over-eater or glutton (I honestly don't know what she is doing with this) is baffling to me. She could have her addicted to something else and or just not at all. Since you already set up that Sherlock Holmes is not real, and that Charlotte's sister Olivia is going to write stories about the man, who cares that you try to mirror every little thing in those stories.
I can't really get a handle on the other characters. Mrs. Watson barely felt in this one. We do have her teaching Charlotte about self defense which I liked.
Olivia Holmes is in and out of this one. She's not really integral to the plot, but having her get romantic notions about someone that may be in danger made me just sigh. I am guessing based no how this book ends, he will pop up in the third book.
Lord Ingram and Charlotte...I don't know. Due to the events in this book one wonders what will happen next. I actually liked the idea of Charlotte getting married to Lord Bancroft (have fun reading about what happens next). At least it would have moved the book to a different place than I think most readers would have expected.
The writing didn't grab me like in the first one and the flow was not good. The only parts I found interesting where getting Charlotte's and Mrs. Watson's POV. I would recommend Thomas cut down on the back and forths to Inspector Treadles in the next one. She could have left him out entirely and nothing would have been missed since he ends up just being a minor player in this. I think we only see him since he will have a larger role in book #3.
The ending felt vaguely unsatisfactory since you have a lot of revelations that didn't quite make sense to me at all. I even re-read some of the sections again and just gave up. I think books like these have to leave clues that readers can pick up on as well. Otherwise it's not really fun to read. You just have the author throwing out twists.