No Good Deeds — Laura Lippman

For Tess Monaghan, the unsolved murder of a young federal prosecutor is nothing more than a theoretical problem, one of several cases to be deconstructed in her new gig as a consultant to the local newspaper. But it becomes all too tangible when her boyfriend brings home a young street kid who doesn't even realize he holds an important key to the man's death. Tess agrees to protect the boy's identity no matter what, especially when one of his friends is killed in what appears to be a case of mistaken identity. But with federal agents determined to learn the boy's name at any cost, Tess finds out just how far even official authorities will go to get what they want. Soon she's facing felony charges -- and her boyfriend, Crow, has gone into hiding with his young protege, so Tess can't deliver the kid to investigators even if she wants to. Time and time again Tess is reminded of her father's old joke, the one about the most terrifying sentence in the English language: "We're from the government -- and we're here to help."