An unusual monograph was published in 2025: its authors (extraordinary researchers, experienced practitioners) offered the readers an analysis of personality of a criminal holding the top position in the criminal hierarchy. This topic is complicated and poorly studied, although characteristics of the mentioned category of subjects is extremely important for successful organized crime combating. The paper reviews specifics of the underworld: its history, hierarchy, spheres of influence. The author analyzes in detail criminal, legal, social, psychological, medical, and biological aspects, including ethnic and geographical features, to be taken into account with regards to thieves-in-law.