New York cop Norah Mulcahaney is back, in typically readable form, but this time O'Donnell seems more interested in dramatizing a social issue--the too-lenient treatment of teenage criminals--than in providing much in the way of mystery. Thus, a few chapters into the book, it's made fairly clear that a group of psycho-kids (not under-privileged) is responsible for a series of thrill-killings--at the Central Park Zoo (the animals and a guard) and in a fancy hi-rise (an aged, famed musician; a mother and daughter). Meanwhile, too, the teenage niece of Norah's cop husband Joe is raped with a bottle by her classmates. ""Rich kids are out for kicks same as poor kids"" is the idea, but O'Donnell lays it on a bit too thick here, with sketchy family histories that hardly explain the rampant sociopathic behavior going on. Still, there's some solid action-suspense in Norah's showdown with one of the knife-wielding kids (she gets nothing but trouble for shooting in self-defense). And there's a bit of deduction when Norah--who must battle red tape and police corruption--figures out which of the kids is the mastermind, setting a trap for him. Well-paced and occasionally scary in its violence, then, but somewhat overdone in its message and short on traditional-mystery satisfaction.