This is book 2 of the "NYPD Red" series.

This note contains spoilers for the book.

Well, by James Patterson and Marshall Karp. Patterson collaborates a lot and publishes a lot of books, so I'm treating the collaborations as by the collaborators. This is not entirely fair, but then treating them as definitely by Patterson is also not entirely fair; though presumably he gets final signoff. He does claim the copyright for himself.

The idea of a special elite unit for responding to crimes against the rich is repulsive. It's bad enough that everybody assumes the police pull their best people for prominent cases; to institutionalize it and limit it that way is disgusting.

But I'll skip that in a book. Having to deal with the politics is real enough, and books select the interesting cases to write about anyway (worse; they make them up!).

A vigilante killing people who got away with crimes isn't that original. Getting them to make moderately-believable confessions on video first is a nice touch though. And of course the obvious happens—they kidnap a woman falsely accused of killing her own baby, who was acquitted at trial but nobody outside the jury box accepts that verdict. Being actually innocent, they're having a harder time getting her to confess.

They turn out to be a pair of rogue cops, who started while in highschool by killing the son of the local mafia Don who was terrorizing their school. One of them stupidly kept evidence from that, and stupidly left it at home (well, accidentally) when he moved out, and his mother when she found it stupidly passed it on to the wife of the mafia Don (who just barely manages to behave civilly enough for the mother not to notice the problem).

So the two vigilantes have both the mafia and the top police after them. This does not end well for them, as you might guess. The innocent woman (who left her daughter home alone too much, but did not kill her even by accident) even gets rescued.