During the peaceful period of Song and Liao, Tang Ziyan, a spy trained by the secret organization "Fenghuo Army", was placed in the Imperial City Department of Kyoto. When she wanted to retire and live a peaceful life with her husband Zhou Qian'an, her husband was captured by the Fenghuo Army and coerced to give Tang Ziyan a new task: assassinate the visiting Northern Dynasty envoy Huang Taidi. During this period, Zhou Qian'an was shot and killed by the Fenghuo Army. Tang Ziyan was determined to overthrow the Fenghuo Army and pretended to be unmoved to continue the next assassination plan, but was surprised to find that the contact person was right next to her. In the end, Tang and Huang Taidi worked together to defeat the Fenghuo Army, quelled a disaster, and Kyoto returned to peace.