Detective Carl M rck of Department Q, Copenhagen's cold cases division, meets his toughest challenge yet when the dark, troubled past of one of his own team members collides with a sinister unsolved murder.

In a Copenhagen park the body of an elderly woman is discovered. The case bears a striking resemblance to another unsolved murder investigation from over a decade ago, but the connection between the two victims confounds the police. Across town a group of young woman are being hunted. The attacks seem random, but could these brutal acts of violence be related? Detective Carl M rck of Department Q is charged with solving the mystery.

Back at headquarters, Carl and his team are under pressure to deliver results: failure to meet his superiors' expectations will mean the end of Department Q. Solving the case, however, is not their only concern. After an earlier breakdown, their colleague Rose is still struggling to deal with the reemergence of her past--a past in which a terrible crime may have been committed. It is up to Carl, Assad, and Gordon to uncover the dark and violent truth at the heart of Rose's childhood before it is too late.