In the late autumn of the 26th year of the Republic of China, Tianjin Wei was shrouded in iron hooves by the Japanese army. Guayi Street in the rain and fog hid countless secrets. The patriotic student Yu Zichen carried the wax pill information that his brother Yu Zimo had exchanged for his life, and ventured into the "Qianyi Bookstore" three times. This was the only clue left by his brother before his death, only the four-character code "paper kite as a note".
Jiang Chiye, the shopkeeper of the bookshop, appears to be a gentle scholar, but is actually an underground member of the Chinese Communist Party who has been lurking for many years. When Yu Zichen said the connection code "Sparks are not afraid of rain", the fate of the two was closely intertwined with Jinmen's anti-Japanese secret line. The information in the wax pill is shocking: the Japanese army's arsenal in Tanggu Port contains mortar ammunition for the southward campaign. If it is not destroyed in time, the front line will fall into a greater crisis.
The Japanese army's search is getting closer and closer, and the secret conversation in the attic of the bookstore is interrupted. Jiang Chiye resolves the crisis with extraordinary calmness; in order to avoid the spy's eyes, Yu Zichen takes over the important task, puts on a plain cheongsam, carries a copper paper kite pendant, and ventures to the "Juxian Tower" in the French Concession to meet the liaison officer "Pigeon". However, the joint site was suddenly surrounded and suppressed, and "Pigeon" died heroically to cover Yu Zichen. Can the information be transmitted safely? Can the arsenal in Tanggu Port be successfully blown up?
