Treachery in Death - J. D. Robb

In this thriller in the #1 New York Times bestselling phenomenon, Eve Dallas tracks down those who break the law-including the ones sworn to uphold it.
Detective Eve Dallas and her partner, Peabody, are following up on a senseless crime-an elderly grocery owner killed by three stoned punks for nothing more than kicks and snacks. This is Peabody's first case as primary detective-good thing she learned from the master.

But soon Peabody stumbles upon a trickier situation. After a hard workout, she's all alone in the locker room when the gym door clatters open, and-while hiding inside a shower stall trying not to make a sound-she overhears two fellow officers arguing. It doesn't take long to realize they're both crooked-guilty not just of corruption but of murder. Now Peabody, Eve, and Eve's husband, Roarke, are trying to get the hard evidence they need to bring down the dirty cops-knowing all the while that the two are willing to kill to keep their secret.