Welcome to the bottom of the human soul. Who is capable of becoming a serial killer, and what should happen in a person's life in order to break the psyche like that? How much pain does a person need to experience in order to turn into a monster that cannot feel and empathize? Is such a person able to change, and is it possible to get infected with someone else's madness? You will find answers to these questions in the new book of the American criminal psychologist M. Knox! You will learn not only about what the psyche of the killers is woven from, but also what world they live in, how they justify themselves, and who supports them.