Veterinarian and ex-Hamburg cop Hauke Jacobs refuses to believe his practice town Schwanitz's legend that as every seven year, medieval raider Viking captain Sven rises from his sea grave to kill two people, but on Baltic peninsula Priwall every one shivers anyway. Local Selchow is found in bed, drowned, so constable Lona Vogt and Hauke's assistant Jule Christiansen superstitiously blame wild Sen, whom fisherman drowned about 10 years ago. While Jacobs and Vogt search for the real, modern killer, his past as key witness in a mob trial requiring witness protection reaches the sleepy harbor town, involving Turks and a maritime smuggling scheme but also a dark personal grudge secret about the Lutheran minster's daughter, whose abuse-murdered daughter Agnes was deemed a previous Sven victim.