It is 12 years since policewoman Lena Jörning (Veronica Ferres) last heard from her sister, when Evelyn (Janna Striebeck) loved the little village on the Baltic coast of Germany in order to escape from the monotony of everyday life. When a body is found in the frozen Baltic, Lena has to take charge. It comes as a terrible shock when the first corpse she has encountered in her career turns out to be her own sister, who appears to be imprisoned in the ice.

A team of CID officers (Detlev Buck and Konstanze Breitebner) arrives to take charge of the case. There are plenty of questions to clear up: when did Evelyn return, and why doesn't Lena know anything about it? Do Evelyn’s husband Claas (Martin Feifel) and Lena’s fiancé Bruno (August Schmölzer) have anything to do with the case? The investigation becomes a dramatic journey into the past for everybody involved, a past which – although Lena hasn't been able to recognize it - still overshadows the present for the entire village.