The 17-year-old student Julia (Mala Emde) appears at the police station and accuses her brother of murdering her classmate Maria. The next morning, Maria's body is actually recovered from the fjord. The investigator duo Klaus Borowski (Axel Milberg) and Sarah Brandt (Sibel Kekilli) find clues as to why Julia's brother could have committed the crime, but the inspectors cannot explain Julia's betrayal. It is only when they discover that she has secretly converted to Islam that light slowly seems to come into the darkness. But Borowski and Brandt are not alone with their investigations: the state security department at the LKA headed by Kesting (Jürgen Prochnow) is apparently pursuing its own unscrupulous interests.