Bill Black is a scary guy: a tall ex-con who rides to work on a Harley, and trails an air of violence wherever he goes. In Macon, Georgia, Bill has caught the eye of a wiry little drug dealer and his cunning girlfriend. They think Bill might be a useful ally. They don't know that Bill is a Georgia Bureau of Investigation agent named Will Trent. Or that he is fighting his own demons, undercover and cut off from the support of Sara Linton—the woman he loves, who he dares not tell he is putting himself at such risk.

Sara herself has come to Macon because of a cop shooting: her stepson Jared has been gunned down in his home. Sara holds Lena, Jared's wife, responsible: The female detective has been a magnet for trouble all her life, and it's not the first time someone Sara loved got caught in the crossfire. Furious, Sara gets involved in the same case that Will is working without even knowing it, and soon danger is swirling around both of them.

In a novel of fierce intensity, shifting allegiances, and shocking twists, two investigations collide around a conspiracy on both sides of the law. Karin Slaughter's latest is both an electrifying thriller and a piercing study of human nature: what happens when good people face the unseen evils in their lives.