What I liked best about this book was the fully rounder-out development of the protagonist, Bess. Strong minded, clear-eyed in her sense of obligation and determined to carry on against all obstacles to get at the truth and see that justice was done. The story is very engrossing despite a couple of quite serious flaws in the telling of it. The main weakness in a departure from easy credibility once you get past midway. At one point there's also an awkward error in logical sequence of "who knew what" (no spoiler here, I'll let other readers find it for themselves and handle it as they see fit).
The time (WW 1) and place (England, mostly London and Kent) are presented surprisingly well given that the book is newly written and the author can hardly have experienced that setting in person. Apart from its 21st century language style, the book could just as well have been written 60 years ago, when stories and heroines like this were more in vogue.
I'll be quite happy to read more from this writer, assuming that more Bess Crawford stories are coming along.