You know, I never have any idea what’s going on in these books and I really appreciate that Thomas has taken a very Holmesian approach to each novel–which is to say, they obvious have a very rich mythology at this point (see: the cast of characters at the start of the novel, which you’d usually associate with some terribly long Russian novel) but also they sort of (?) stand alone if you’re willing to be confused and accept that you’re not getting as much nuance. Or, like me, you can’t remember enough of what happened in book seven, let alone books one through six (or two through six, maybe, one had a lot of the standard Holmesian origin story).
That being said, if you’re not like me and do remember what’s going on, you might be mildly frustrated with the amount of recapping that characters do, as not all of it (very little of it, to be fair) is done in a subtle, integrated way. With only one story written up by Livi (taking on that element of the Watson role), there’s not an easy narrative framing device to remind us readers of the web of Moriarty/illegitimate brothers/legitimate but terrible brothers/sisters/nieces/nieces who are actually daughters that Thomas has spun over the past eight books.
Could I keep track of what was going on even in this book? No! There are too many characters with the same last name whose only differentiation is their prefix. I never fully understood why Miss Harcourt was so enamored of her cousin(?) Mrs. Meadows-slash-Farr, nor did it really add much to the story other than color (which it didn’t really lack for). It’s not until the latter parts of this book that things start to click into place, and therefore get engaging in a classic mystery way. I’m sure I’ll find out the ninth book in this series is out about six to twelve months after the publishing date, and read it with a similar mindset then.