On a night before the Qing Dynasty was about to fall, two screams were heard on the streets of the French concession in Tianjin. After a flash of blue light, the heads of two foreigners fell to the ground. The killer was the mysterious masked woman "Blue Viper". Private detective Dongfang Hongfei was commissioned by the magistrate of Tianjin to investigate the case, and unexpectedly discovered new clues about the long-lost national treasure of the palace, the "Eight Horses Painting".