West Cork. November 1920. The Irish War of Independence rages. The body of a young woman is found brutally murdered on a windswept hillside. A scrap board sign covering her mutilated body reads 'TRATOR'. Traitor. Acting Sergeant Sean O'Keefe of the Royal Irish Constabulary, a wounded veteran of the Great War, is assigned to investigate the crime, aided by sinister detectives sent from Dublin Castle to ensure he finds the killer, just so long as the killer he finds best serves the purposes of the Crown in Ireland. The IRA has instigated its own investigation into the young woman's death, assigning young Volunteer Liam Farrell - failed gunman and former law student - to the task of finding a killer it cannot allow to be one of its own. Unknown to each other, an RIC constable and an IRA Volunteer relentlessly pursue the truth behind the savage killing, their investigations taking them from the bullet-pocked lanes and thriving brothels of war-torn Cork city to the rugged, deadly hills of West Cork.