In 1277 England, the discovery of a Roman hoard sparks a deadly shadow war between English and French spies. On the streets of Paris, French agents seize an English agent, Lady Clemence d'Lisle, and she disappears. After the crown declares the hoard treasure trove, thieves brazenly steal the king's gold en route to Westminster, and the King's Man, Simon Lowys, must recover it. As he untangles a complex web of murder, Welsh rebels, deception, and elusive assassins, Simon questions his calling as a man of law when he sees justice obscured by duplicity and lies. Thwarted at every step, Simon realises that as he closes in on the truth, the greatest deception of all may come from the very woman he loves.