In the Shanghai Concession in 1937, Su Wan, an underground party member, disguised himself as an employee of a foreign bank and was responsible for delivering Japanese military intelligence. However, during a mission, he unexpectedly cooperated with Gu Yan, a Kuomintang agent also disguised as a businessman. The two were suspicious of each other at first, but gradually trusted each other after working together many times to deliver intelligence and avoid being hunted by the Japanese army. When Su Wan's identity was exposed, Gu Yan gave up the opportunity to evacuate and helped her cover up. The two made an agreement under the neon lights of the concession: "Protect the home and country first, and then renew their relationship."
