The Dark Hours by Michael Connelly

 Dark Hours is the latest Harry Bosch/Renee Ballard adventure. Renee is still a cop on the night shift, which was intended to punish her but which she discovered she really likes. It's New Year's Eve and she's paired with a burned-out partner, Lisa Moore, to work on tracking down 2 serial rapists. While they're out, they get called to a potential homicide. A man is dead at a street party, supposedly hit by a random bullet when people began firing into the air at midnight. But Renee thinks it might have been murder--and is determined to solve the case before it gets taken away from her. She is also still working on the rapist case--now without her crabby partner, who has taken off for the weekend. While investigating the murder, she realizes the gun used was also used in a cold case of Harry Bosch's. Soon the two of them are (under the radar, of course, since Harry is retired) working both cases--and getting better results than the people who are supposed to be actively investigating.

I like both of these characters and love having them work together. The story ends with a cliffhanger and it will be interesting to see which direction Renee chooses.