Louisiana Sherriff’s Detective Dave Robicheaux and his longtime friend and partner, Clete Purcel, are vacationing in Montana when a series of suspicious events leads them to believe that their lives --- and the lives of their families --- are in danger. Robicheaux's daughter, Alafair, thinks she sees a familiar face following her around town. But how could convicted sadist and serial killer Asa Surette be loose on the streets of Montana?