Baltimore PI Tess Monaghan knows what to do with a jerk who prowls the Internet looking for love in all the wrong places: pretend to be smitten, slip one of his own date-rape drugs into his drink, cover him with depilatory cream, and leave him in a public place so he'll be too ashamed to do it again. It's hard to follow an opening chapter like that, but Lippman manages it nicely, putting her smart-mouth series sleuth in court-ordered anger-management counseling. The sessions with her shrink spur a most uncharacteristic-for Tess--reflection on five cold-case homicides she's investigating for a foundation lobbying for increased funding for domestic abuse programs. They don't seem to be connected, but with the help of the retired Toll Facilities cop who discovered the head of one of the victims in the middle of his bridge, Tess discovers a serial killer no one even knew existed--until he made Tess his next target. This is the seventh outing in a lively, original series that keeps getting better and better.