In 1935, Shanghai was in turmoil. After the mysterious death of her father, Shen Qingci, the daughter of the Shen family, accidentally discovered an ancestral encrypted notebook. This seemingly ordinary book actually contained important information related to the country's security, making her the target of various forces overnight.
At a critical moment, she was rescued by the mysterious patriotic officer Lu Chengze. Lu Chengze appears to be a translator working for the Japanese army, but in fact he is an intelligence officer lurking within the enemy. The two became connected because of the code book. In order to interpret intelligence and deliver messages, they had to trust each other and fight side by side.
Faced with the relentless pursuit of the traitor agent Zhao Kun and the rigorous searches of the Japanese army, they passed on information amidst the light and shadow of swords and stuck to their original aspirations in the ups and downs of troubled times. The righteousness of family and country is intertwined with the love of children. Can they protect information and each other in the flames of war, and fight for a bright future for the country?
