London - 1753. Its perilous streets were overrun by armed gangs, corrupt night watchmen and thief takers. However, two magistrates felt it their duty to enforce the law and to build the institutions that now protect the innocent. Brothers Henry (Ian McDiarmid) and John Fielding (Iain Glen) investigated the lives and crimes of prostitutes, pimps, gamblers and villains in Covent Garden, the centre of London's vice trade. They and their infamous 'Bow Street Runners' would change the face of the law for good.