THOSE WHO KILL follows criminal commissioner Katrina Ries Jensen and legal psychiatrist Thomas Schaeffer who are part of a special investigation unit at Copenhagen Police investigating serial killings. The cases investigated by this unit are rarely rooted in traditional motives and patterns. In these cases, the motives are far more complex and the threats more dangerous, because the crime is rarely a goal in itself but rather a means to an end. A way for the perpetrator to redeem his fantasies and pain. To solve these cases, our main characters have to put themselves in the killer's place and understand his psychology, his fantasies and his longings. Only when they understand why the killer kills, can they hope to catch him.