The film is set in western China in 700 during the Tang Dynasty, and revolves around two protagonists, the first of which is Lieutenant Li of the Chinese army. Li's refusal to kill Göktürk women and child prisoners causes a mutiny, leading him to be expelled from the army and become a fugitive, traveling through the Gobi Desert. He eventually comes across a caravan which carries a powerful, mystical relic accompanied by a Buddhist monk. Li protects the caravan from Göktürks as well as the overlord of the region, Master An, who is hired by the Göktürk Khan to seize the relic.

The second protagonist, a Japanese emissary, Lai Xi, is ordered by the emperor of China to kill the fugitive, Li. In a twist of fate, Lai Xi realizes that the caravan is on a mission and helps Li to defend it, and ensures that it arrives at the capital safely. They promise to fight each other only after their duty is done, although that battle never comes to pass.