A century after the collapse of the High Tang, the Central Plains dynasty and the Turkic Khaganate fight a final war of attrition beyond Yanmen Pass. General Xiao Chengyan has guarded the frontier for ten years, earning the name “Ironblood Great Wall” and striking fear into enemy ranks. But a secret letter from a Turkic spy draws him into a deadly struggle between the imperial court and the regional warlords.
The ninth princess of the Turks, Ashina Yun, disguises herself as a princess sent for a political marriage and infiltrates the Tang camp, hoping to clear her family of the charge of colluding with the enemy. Amid the blood-red smoke of war, she crosses paths with Xiao Chengyan. As the wolf banners of the frontier mingle with the war drums of the Central Plains, the two go from clashing blades to entrusting each other with their lives, unaware that the secrets they carry have long been etched into their fate
He is the eldest son of the Turkic khagan, raised far from home. She is the avenging sword of a renowned Central Plains general's orphaned child.
On the battlefield at Yanmen, the blood-red setting sun stains more than their armor. It colors two lives bound together by love and hatred across the divide between their peoples: “I would offer you a hundred thousand cavalry as your bride price, yet the enemy still lies a thousand miles away. Dare you make the rivers and mountains our game board and face life and death at my side?”