The opening episode is the first documentary film to examine the case of Joanna Dennehy, one of only a handful of known British female serial killers. Growing up, Dennehy was a normal happy child. She excelled at school and sports and her parents dreamed that she would end up at university studying law. That the thirty something mother-of-two became responsible for the horrific murder of three men in the space of ten days shocked those around her.

Not all psychopaths are killers and most usually operate alone, but John Duffy and David Mulcahy are a rare exception. Lifelong friends since their schooldays in Haverstock, north London, they were responsible for a four-year spree of rape and murder across London during the 1980s. They became known as the Railway Killers, due to their targeting of lone women around railway stations. It was this behavioural consistency that would eventually lead to their capture.

David is in America to analyse how the unusual behaviour displayed by Dennis Rader as a child gave an early indication that he would grow up and become a psychopath.

Professor Wilson investigates Steve Wright, who strangled five women from Ipswich in December 2006.

Documentary in which criminologist professor David Wilson explains how an almost-perfect collision of bad nurture and bad genes produced the charming but vicious psychopath Patrick Mackay. Mackay began by throwing a man off a bridge, then fed his drug habit by robbing and killing wealthy west Londoners in their homes, before killing a priest with an axe.

A respectable businessman by day, a psychopathic sexual predator by night, Moore was dubbed 'the man in black' after committing a series of violent sexual assaults on men for over forty years, culminating in the murder of four men in the space of three months in 1995.