The story is based on a mysterious cavalry unit in the Sui and Tang Dynasties - the Eighteen Riders of Yanyun. They were ordered by the court to guard the border. They were well-trained and highly skilled in martial arts, which frightened the enemy. They were the strongest special forces in the era of cold weapons! During a pursuit mission, the Eighteen Riders accidentally discovered that the weapons held by the foreign enemies were made with the unique soil-covering and blade-burning technology of the Sui Dynasty. The court has been infiltrated by traitors, and the foreign vassal army is approaching. How will the battle-hardened Eighteen Riders pass on this important intelligence and protect the thousands of people behind them?