London. A city where no one feels safe and one man's crime is another man's justice. A paedophile is brutally murdered, and to protect other known offenders the police must haul the families of their victims down to the station for questioning. It's just another day in the life of DI Will "Staffe" Wagstaffe. In this case nothing is simple, least of all Staffe's personal life. He finds the boundaries between right and wrong have been blurred, but the main question remains: just how far would you go to protect your children?