1261. Oxford, England. An envoy returns from the land of the Tartars to meet with an English scholar and share a deadly secret. The two men vow that the knowledge of gunpowder must die with them as the consequences are otherwise too fatal to contemplate. 1290. After his quiet life is shattered by tragedy, blacksmith Jared begins a pilgrimage from England to the Holy Land. The adventure that follows sees Jared join a holy crusade and encounter men from distant Cathay who harbour the secret of huo yao. So begins one man's obsession with the powder of death and a king's resolution to change the very nature of warfare . . .