Brothers Jack and Tony Finn work together in the same division of the National Serious and Organised Crime Unit. Being the only officers of their kind, they're feared by colleagues and criminals alike. Jack, however, is leading a secret double life – having fallen in love with Tony's wife, Rachel. Forced to put their personal differences aside for the sake of their profession, Jack and Tony investigate the likes of crime families, Triads, gangland killings, extortion and major drug suppliers, all whilst trying to battle with their own demons.