A clever child from a loving home, William Cornick shocked Britain when he stabbed his teacher, Ann Maguire, to death at his school in Leeds. This documentary explores the possible causes of his pathological hatred.

In 2009, Rosalyn Hunt and Desmond Thorpe were murdered by teenager Lorraine Thorpe and her accomplice. Was Britain's youngest double female killer always destined to kill?

15-year-old James Fairweather terrorised a local community with random deadly attacks that left two people dead. What made him carry out such brutal murders?

Teenage lovers Kim Edwards and Lucas Markham were convicted of murdering her mum, Elizabeth and younger sister, Katie in April 2016. What led them to kill?

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In 2013, Sean McHugh, went to a laundrette in Anfield, Liverpool to do his washing, only to be stabbed by a teenage gang. What made them kill an innocent man?