In February 1997, Roger Andrews is confronted in his home by a man holding a gun. In a split second decision Roger fights back with his own pistol and shoots the man 3 times. The man survives and is arrested by the police. Quickly links between the man arrested and another crime emerge - the murder of a retired town clerk in Ramsgate in 1996. In June 2010, 14-year-old Lillian Groves was killed outside her home in New Addlington in Surrey by speeding motorist John Page, who had been smoking cannabis. This is the story of Lillian’s parents’ fight to change the legal system that had allowed this man to escape a fitting punishment.

• Robert Rinder