It's Dr. Kay Scarpetta's birthday and she's about to head to Miami for a vacation with her FBI profiler husband Benton Wesley when she notices seven pennies on a wall behind their Cambridge house. Is this a kids' game? If so, why are all of the coins dated 1981 and so shiny it's as if they're newly minted? Then her cellphone rings, and Detective Pete Marino tells her there's been a homicide five minutes away. A high school music teacher has been shot with shocking precision as he unloaded groceries from his car. No one heard or saw a thing. It's as if God did it.

In this 22nd Scarpetta novel, the master forensic sleuth finds herself in the middle of a nightmarish pursuit of a serial sniper who seems to leave no evidence except fragments of copper. The shots are so perfect, they cause instant death and seem impossible, and the death scenes aren't crime scenes because the killer was never within hundreds of yards of the victims. The victims seem to have nothing in common, and there is no pattern that might indicate where the Copperhead will strike next. First New Jersey, then Massachusetts, and then into the murky depths off the coast of South Florida, where Scarpetta dives a shipwreck, looking for answers that only she can discover and analyze. There she must face an unthinkable truth that points in the direction of her techno genius niece, Lucy, Scarpetta's own flesh and blood.