Actually, 3.5. I am a big Michael Connelly fan...and Harry Bosch too. For some reason, the unraveling of the mysteries in this one didn't hold my attention and enjoyment as much as prior ones have. There are two simultaneous story lines: a major opioid ring and a cold case Harry is working on in which is honor is impugned.
The last chapter redeems... you hear more of Harry's (and probably Connelly's) view of good and evil and how the world runs.