It is the third year of Daye (607 CE). The people of Sui Dynasty are living in poverty under the brutal rule of Emperor Yang Guang. In the desert fringes of this empire is a traveling swordsman named Dao Ma. He's a skilled bounty hunter who hopes to pay off his debt to his foster godfather while looking after his three-year-old son, Xiao Qi.

When Dao Ma takes on an escort mission to bodyguard an enigmatic fugitive to the imperial capital Chang'an, he treats it as a simple high-paying job. Little does he know that this client is a dangerous mystic twirling strings that could uproot the empire from its foundations.