In a newly unified empire ruled by the Qin Emperor, young orphan Jing Tianming and his protector, Ge Nie, are forced into a life on the run. Once celebrated as Qin's strongest swordsman, Nie is now branded a traitor, and Tianming suffers from an unknown illness. Bound by an old promise, Nie is determined to protect Tianming as enemies encircle them.

When an elite unit of three hundred men is sent to capture them, Nie cuts them down but is left gravely wounded. While struggling to keep him alive, Tianming accidentally runs into Xiang Shaoyu—a proud and skilled fighter from the fallen Chu Kingdom who is determined to reclaim his people's lost honor. The trio seeks refuge in the reclusive Mohist School, one of the most notable factions resisting Qin rule.

As Nie receives much-needed medical attention from the Mohists, the Qin Emperor enlists the help of a cunning man named Wei Zhuang. An old rival of Nie and a disciple of the same master, Wei Zhuang and his group of deadly assassins will stop at nothing to see Tianming's group dead.