October 1816 and the body of Harry Gadd, a twelve year old, homeless, street urchin is dragged from lake in St. James's Park. He has been murdered and sexually assaulted. The Bow Street police force, with limited resources, are happy to write this off as another unsolved crime, but Tom Thewles, a newly recruited patrolman, has a very private reason for wishing to avenge his murder. He persuades his partner, Constable Jack Black, to defy orders and investigate the case in their spare time. Through a quirk of fate, obeying orders from no less a person than the Duke of Wellington, the pair are assigned to investigate the disappearance of a young gunsmith, Eli Turnbull. However, their investigations are hampered by mysterious restrictions imposed on them by two Government ministries. Tom, undeterred, continues and slowly unearths new evidence, which shows that, not only are Harry's and Eli's deaths interconnected, but that the murderer is the very man behind Tom's personal obsession to catch Harry Gadd's murderer. The murderer is finally brought to trial, helped by the courage of Emma, Jack Black's daughter. But will British justice prevail or does some outside force intervene?