The author of this book played a major part in the FBI's development of psychological profiles for serial killers, he even invented the term serial killer. Whilst Thomas Harris made Ressler's work famous in fiction, Ressler did it for real. His work in the Behavioural Science Unit led him to meet some of the most notorious criminals of the 20th century - Ted Bundy, Charles Manson, John Wayne Gacy and many more. In this book, Ressler describes the process of catching these men.