The medical sage Mr. Nangu was exterminated because of a medical book "Yanyun Jue" that wrote the best martial arts in the world. Before he died, Mr. Nangu asked the world's best swordsman Hua Chenhan to protect his son Mo Xuan and go to Zixuan City to find his old friend Kong Chan for help. Unexpectedly, before Hua Chenhan arrived, Kong Chan had already defected to the imperial court. Hua Chenhan, who had developed a brotherly relationship with Mo Xuan along the way, could not bear to leave Mo Xuan behind. In order to prevent "Yanyun Jue" from being obtained by bad guys, and for the sake of peace in the world, the two embarked on the road of becoming enemies of the world...