Secret War in Tongcheng

To complete his mission and unearth the traitor who sold out the organization, Lan Yuhang poses as a son-in-law and marries into the wealthy Gao family. He becomes one of the Gaos, starts a silk business with his wife, Gao Qiqin, and uses his merchant status to outmaneuver Japanese spies and Wang Jingwei's puppet agents. He sets traps and finds ways out, always planning before he acts. After enduring countless hardships and dangers, he finally exposes the traitor and eliminates a deeply entrenched collaborator.