1943, Shanghai occupied area. Due to a sending and receiving error, underground party telegraph operator Shen Yunhe intercepted a top-secret drawing of the Japanese army - it was marked with a reconstruction plan for the "Western Underground Arsenal". The blueprint is encrypted and must be deciphered within three days, otherwise the blueprint will self-destruct and the information will be invalid. At the same time, Zhao Wenxuan, a former classmate and now a traitor translator, came to the door and claimed that he could help him interpret the drawings, but the condition was that he took him to escape Shanghai. Shen Yunhe must find out the truth about the drawings from Zhao Wenxuan's lies and the Japanese army's pursuit within three days, and keep the secret base of the underground bookstore. A wrong telegram leads to a shocking conspiracy; a traitor hides a fatal bargaining chip.
