Who are serial killers? How to search for them? What is behaviorism and how is it used in detective work? The reader will find a fascinating story about this based on real incidents in the documentary crime story of John Douglas, one of the prominent FBI employees who has long specialized in creating a unique method of searching for criminals using a psychological portrait. The book, written by him together with Mark Olshaker, will be a fascinating read for fans of the detective genre and a necessary guide for people who deal with the underworld as part of their duties.