Neurologist Jonathan Pincus probes into the lives of numerous serial killers and other violent criminals to find out what triggers the violent instinct. Working with forensic psychologist Dorothy Lewis, he investigates their family backgrounds and medical history, discovering that virtually all the murderers themselves suffered severe abuse as children, which permanently damaged their developing brains. In these stories, Dr. Pincus finds that violent criminal behaviour cannot be solely attributed to genetics - rather, it is the catastrophic product of a brain that may be born predisposed to violence coupled with an abusive environment. Focusing on these critical factors, how can we identify potentially violent persons from a young age before the damage becomes irrevocable? How can we rehabilitate violent criminals and at the same time safeguard against their committing future crimes?