Dr. Michael Stone uses his own "scale of evil" to rank and measure the depravity found within some of the most deadly criminals of all time. Profiles include: Ted Bundy, Dennis Rader (the "BTK" killer), Aileen Wuornos, Tommy Lynn Sells and Jeffrey Dahmer. Forensic psychiatrists, neurologists and psychologists use scientific evidence to understand the thinking of criminal masterminds. Experts are turning to science hoping to use this information to help prevent future criminal development. After a long hiatus, the series returned in 2014 with fresh episodes hosted by forensic psychologist Kris Mohandie. Also back is the infamous scale, a popular feature with viewers.