In December of 2014, 19-year-old Jessica Chambers was set on fire in her car on an old country road in her rural Mississippi town. Jessica survived long enough to give a few clues as to who committed this unspeakable crime, but it would prove near impossible to apprehend her killer.

When 15-year-old Joanna Dennehy first met 20-year-old John Treanor in her hometown of St. Albans, Hertfordshire in the United Kingdom, the romance was like something out of “Trainspotting”. It predictably descended into madness over the course of 12 years, because Joanna had been hiding a secret....