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.