Walt Longmire has been sheriff of Wyoming's Absaroka County for almost a quarter of a century and has meted out justice with charm and a high-powered sense of humor, but when Walt tags along with good friend Henry Standing Bear on a trip to Philadelphia, he's in for a shock. When a vicious attack on his daughter Cady leaves her near death, Walt discovers that she has unwittingly become embroiled in a deadly political cover-up.

With Henry, Deputy Victoria Moretti, the entire Moretti clan of Philadelphia police officers, and Dog as backup, Sheriff Longmire intends to introduce a little western justice from his saddlebag of tricks to the City of Brotherly Love, where no act of kindness goes unpunished.