In the 8th century Tang Empire, Chang'ansi is an intelligence agency that protects the Empire and the Capital. Li Bi is the de-facto leader of the agency and an ally to the crown prince. When the emperor gets weak and the Crown Prince and the Chancellor clash over the power, Li Bi finds out a spy from Turk plans an attack during the festival. The agents only have 24 hours to stop the possible threat. As the first attempts to capture the terrorist failed, Li Bi brought the wild card: Zhang Xiao Jing, a death row prisoner who worked nine years as a police chief in Chang'an. Li Bi asks Zhang's service in exchange for the pardon. Desperate to survive, Zhang accepts the impossible task.

In the 8th century Tang Empire, Chang'ansi is an intelligence agency that protects the Empire and the Capital. Li Bi is the de-facto leader of the agency and an ally to the crown prince. When the emperor gets weak and the Crown Prince and the Chancellor clash over the power, Li Bi finds out a spy from Turk plans an attack during the festival. The agents only have 24 hours to stop the possible threat. As the first attempts to capture the terrorist failed, Li Bi brought the wild card: Zhang Xiao Jing, a death row prisoner who worked nine years as a police chief in Chang'an. Li Bi asks Zhang's service in exchange for the pardon. Desperate to survive, Zhang accepts the impossible task.