A 17 year old inmate raped and killed in one of Denmark 's prisons . For Katrine being the case a strong meeting with a past she 'd rather forget , and she goes to attack the system that made the attack possible . When another prisoner killed in the same way , it becomes clear that a serial killer is loose behind bars. The case attracted great attention in the press , and the police receive massive criticism that such a thing at all can happen in a Danish prison . Have criminals less entitled to protection than others? Katrine and Thomas are working under intense pressure to narrow down the culprits in an environment marked by hatred, violence and revenge. An environment that penetrates under the skin of them both, and provokes sides they would rather not acknowledge .