A well-crafted plot and flesh-and-blood characters lift Horn’s superior third Sam Dawson mystery (after 2015’s When Good Men Die). Sam, a gifted photographer whose images all tell a clear story with “a beginning, a middle, and an end,” has had the ill luck to repeatedly make grim discoveries. He makes another one while walking his dog in Wyoming’s Medicine Bow National Forest—the frozen corpse of a 12-year-old girl. The coroner’s initial verdict is that the child, identified as Lilly Darnell, who went missing in Colorado months earlier, died of exposure, but further testing reveals the presence of ketamine, a date-rape drug. The prospect that she was abused becomes more likely after Lilly’s image appears among the photographs of naked children found in the possession of Oscar Roberts, who has harassed Annie George, Sam’s publisher and former significant other. The investigation into Lilly’s fate builds toward a powerful, unexpectedly moving conclusion. Fans of regional whodunits will be rewarded. (BookLife)