Two of Scotland Yard's finest-who happen to be married-navigate darkest London to solve a series of murders that blur every line between right and wrong.
 
Chief Inspector Michael Sinclair, also known as Lord Acton, and rookie detective Kathleen Doyle ruffle more than a few feathers at CID Headquarters when their relationship comes to light. But office politics quickly become trivial amid a rash of underworld murders. As the body count climbs, Doyle uncovers a vicious war over lucrative turf between the Russian mafia and an Irish terrorist group. But their acts of revenge are almost too much for Scotland Yard to keep up with-and when Acton seems unusually troubled by the crimes, Doyle wonders what sparked the conflict in the first place.
 
Perhaps there's nothing more to it than under-the-table business dealings gone awry. Or perhaps a single act of vigilante justice ignited a brutal battle. As Doyle and Acton fight not to become the next victims, they'll find that the truth may be best left unspoken, and retribution may be best left to fate?