A teenager is found dead at the beach with hands and feet tied up. The post mortem reveals that he was still alive before the tide came in. The mysterious part is that in Hamburg a similar crime was committed. Is this the work of serial killer? To find that out police inspector Jana Winter consults her colleague from Hamburg. While they are warming to each other Jana receives strange phone calls where someone is playing a children's song to her. She begins fearing for her own child.