The latest (as I type) book from Michael Connelly, and it's the expected page-turner (or screen-swiper, since I read it on my new Kindle). The front cover bills it as "a Renée Ballard and Harry Bosch novel".
Harry is retired, and Renée, once fired, is now rehired. By the LAPD. She was urged to do her own thing, write her own ticket, at the end of the previous book, The Dark Hours. So she set up a unit to investigate cold cases, hopelessly ancient crimes that might be solved by modern investigatory technique. She enlists Harry as one of her ragtag team members; he gets on board in order to investigate his "white whale" case: a gruesomely murdered family buried out in the desert.
But Renée's unit is a political creation, and she has to bend to political reality: a powerful LA pol wants to know who killed his sister years back. Early on, Bosch suggests that sophisticated DNA analysis be performed on an old bit of evidence, and (what do you know) that links the sister's homicide to a different murder, also long ago. Pretty soon, a suspect comes into focus, and a cat-and-mouse stalking begins.
No spoilers, but Harry is acting a little strange here, not "playing by the rules", more like a loose cannon than usual. But he has his reasons, and they aren't revealed until the very end of the book. Which made me pre-order Connelly's next book, due out in November.