In the Shanghai Concession, female agent Shen Ruoxi uses the singer "Nightingale" as a cover to collect Japanese military intelligence. She meets Gu Yan, an upright reporter. Gu Yan realizes Ruoxi's identity but chooses to keep it a secret. The two supported each other in the undercurrent of the concession, Ruoxi passed on information, and Gu Yan used his pen to expose the Japanese conspiracy. In the process, feelings gradually develop, but due to their identities, they face life and death tests at any time.
