Some crimes go unnoticed. Some criminals go free. These cops go after them. 

Chief inspector Matthias Steiner has been heading the Department of Unsolved Crimes for three years now. Thanks to his dogged persistence and to the tireless fieldwork of his loyal teammate Julia, he's put more than one perpetrator of the "perfect crime" behind bars.
To celebrate their success, Steiner's boss rewards them with a new teammate, the eager, go-get-'em rookie Andreas. Their first case together arrives in the form of a little girl whom the police have found wandering alone in the city. Steiner is intrigued when she says that her name is Britta Leschkov, since he remembers that a child of the same name died of poisoning six years ago.
He personally returns the child to her parents, who react so strangely that he and his colleagues reopen the investigation into the death of the first "Britta." What they uncover is a sordid tale of hatred, abuse, dependency and murderous revenge.