A six-year-old girl is found in the Norwegian countryside, hanging lifeless from a tree with a jump rope around her neck. She is dressed in strange doll's clothes. Around her neck is an airline tag that says "I'm traveling alone." A special homicide unit in Oslo re-opens with veteran police investigator Holger Munch at the helm. Holger's first step is to persuade the brilliant but haunted investigator Mia Kruger to come back to the squad--she's been living on an isolated island, overcome by memories of her past. When Mia views a photograph of the crime scene and spots the number "1" carved into the dead girl's fingernail, she knows this is only the beginning. She'll soon discover that six years earlier, an infant girl was abducted from a nearby maternity ward. The baby was never found. Could this new killer have something to do with the missing child, or with the reclusive Christian sect hidden in the nearby woods? Mia returns to duty to track down a revenge-driven and ruthlessly intelligent killer. But when Munch's own six-year-old granddaughter goes missing, Mia realizes that the killer's sinister game is personal.