The series "Those Who Kill" is a psychological detective story about police partners obsessed with the secret motives of criminals. She is Catherine Jensen, a young specialist who recently joined the homicide investigation department as an intern. He is Thomas Schaeffer, an experienced and self-absorbed intellectual investigator. At first, these two are soaked in mutual dislike for each other, but soon it becomes clear that they share a common professional interest in the psychology of maniacs and the insane.