I had to remind myself -- because this has been a problem for me before with anticipated books -- that It Would Almost Certainly Be Very Much Like Other Books By This Author, and I shouldn't expect anything new or amazing.
The main pieces are present. A prologue when the female protagonist was young when something Very Traumatizing happened, that ends on a bit of a cliffhanger (the reader doesn't not learn what happened to all the participants of that event until much later in the book). The grown-up protagonist, a short, slightly built yet nevertheless attractive in a somewhat unconventional way woman has recently experienced a loss (this time, grandma died, leaving her the hotel chain) and then is called to revisit the past trauma. The hotel chain is Arizona and the past trauma is on one of the San Juan Islands, so the locales are familiar as well.
There's a soon-to-be-ex-boyfriend we see get dumped. The soon-to-be boyfriend appears as the contractor who does hotel security for her. Off they go to the San Juans, where things get murky fast, rapidly pulling in a wealthy family whose son is running for the Senate and whose other son is scary-crazy (as in: torture small animals and arson kind of scary-crazy).
The titular sister isn't a bio-sister -- she eventually shows up with the brother of the security guy. The secondary romance in this book is well developed and is very clearly a nerd romance. I really liked Abe.
If you've read a bunch of JAK, well, this is about what you'd expect, on the higher quality side. If you've never read JAK, I'm not sure this is a good place to start. One of the issues -- common to many romance authors who have been writing for decades -- is that while they age their protagonists somewhat, they don't _act_ like people that age in the time frame of book publication. They act like people somewhat older than that, somewhat in the past. Like: these people watch the evening news, rather than surf on a laptop or mobile device, to wind down in the evening. Demographics say: nope. Sure, sure. You know an exception. But there are a lot of details like this.
I liked it enough to re-download _Trust No One_ for a reread, and of course whenever JAK puts something new out, under any of her names, I'll buy it and read it.