Are serial killers literally different from the rest of us? And, if so, how are they different? Neuroscientist Jim Fallon thought he'd uncovered the defining characteristics of the "killer brain," only to discover later that he too had the the brain and the genes of what he calls a "really bad news character." So why wasn't Fallon a killer? This film uses Jim Fallon's story to explore this question, illuminating the neurological and genetic bases of aggression, nature/nurture and epigenetics along the way, and giving a new angle on the age old question of whether what happens to us in early childhood can send us in one direction or another.