One of Us opens with a girl running for her life. She and her friends are being stalked, hunted by a young man in a police officer's uniform on the small Norwegian island of Utøya. They lie down in the woods, pretending they're dead, hoping the man will see them and move on. He doesn't. He shoots the girl in the head, shoots her friends in their heads, point blank, execution-style. In search of new victims, the man moves on. But almost four years after that July day when 77 people, many of them children, were slain in cold blood, the nation of Norway still struggles to move on.