For his first 58 years, James Fallon was by all appearances a normal man. A successful neuroscientist and professor, he'd been raised in a loving family, married his school sweetheart and had three kids and lots of friends. Then he learned a shocking truth that would not only disrupt his personal and professional life, but would lead him to question the very nature of his own identity. While researching serial killers, he uncovered a pattern in their brain scans that helped explain their cold and violent behaviour. Astonishingly, his own scan matched that pattern.