This is the second book in a series. While it can be read independently, and probably makes sense on its own, you’d be better off starting with book one, A Study in Scarlet Women.
From Goodreads:
Being shunned by Society gives Charlotte Holmes the time and freedom to put her extraordinary powers of deduction to good use. As “Sherlock Holmes, consulting detective,” aided by the capable Mrs. Watson, she’s had great success helping with all manner of enquiries, but she’s not prepared for the new client who arrives at her Upper Baker Street office.
Lady Ingram, wife of Charlotte’s dear friend and benefactor, wants Sherlock Holmes to find her first love, who failed to show up at their annual rendezvous. Matters of loyalty and discretion aside, the case becomes even more personal for Charlotte as the missing man is none other than Myron Finch, her illegitimate half brother.
In the meanwhile, Charlotte wrestles with a surprising proposal of marriage, a mysterious stranger woos her sister Livia, and an unidentified body that surfaces where least expected. Charlotte’s investigative prowess is challenged as never before: Can she find her brother in time—or will he, too, end up as a nameless corpse somewhere in the belly of London?
Now, there are several downsides to having sped through the audiobook version of this in about 24 hours, and having finished the book over a month and a half ago. While I remember very much enjoying it and thinking it builds excellently on the very strong beginning of the series, the details of the plot are decidedly hazy to me (it’s a bit tricky for me to recall exactly what was revealed in each of the three books, as I read all of them in a week quite some time ago now).
Full review on my blog.