After the Battle of Songhu, Shanghai fell. Underground worker Lin Xiang (played by Aaron Kwok) was ordered to come to Shanghai, which was full of dangers, to rebuild the underground anti-Japanese front that was destroyed by the enemy. Here he met Lan Fang (played by Zhao Liying), who was simple but had a strong sense of justice. This temporary "underground party couple" will join hands in a thrilling life-and-death battle with the Japanese invaders and the puppet government spies in the flames of war...