"Dunkelfeld" leads the secret of the previous three rbb "crime scenes" with Nina Rubin (Meret Becker) and Robert Karow (Mark Waschke) to the final climax. The mystery surrounding Karow's past and the death of his partner Gregor Maihack, who was shot dead two years ago during an undercover operation, is solved. The exact circumstances of death are still unclear. Was Karow himself involved? Now the key witness Andi Berger (Robert Gallinowski) wants to make the decisive statement. But on the way to the public prosecutor Hemrich (Holger Handtke), Karow and Berger are ambushed. Berger dies before he can tell Karow where the cellphone video showing Maihack's death is hidden. A little later , Gregor Maihack's widow Christine (Ursina Lardi), with whom Karow had a relationship years ago, is kidnapped.
And shortly afterwards Karow himself disappeared. On the very day that Nina Rubin took the day off to celebrate her son Kaleb's (Louie Betton) bar mitzvah, she and Anna Feil (Carolyn Genzkow) have to find out where Karow is and if he's still alive. The search becomes a race against time. "Dunkelfeld" leads Robert Karow and Nina Rubin deep into a deadly jungle of drugs and corruption. And to the question: What can be seen on the mysterious mobile phone video? Does Robert Karow actually have anything to do with his partner's death?