The story follows police officers Kata and Arnar, in charge of investigating gruesome murders from Iceland’s first serial killer. The unlikely pair slowly starts connecting the case to a mysterious and abandoned boys’ home named “Valhalla”.。Sam's cases involve a series of revenge killings by a former Auschwitz prisoner| the mysterious deaths of teenage girls killed 15 years apart in Norway| a suspicious suicide and a beautiful Nun in a convent by the sea - very different stories, all employing Sam's expertise to the maximum.。