The story takes place in 1984. Ma Dong (Hu Jun) is a national security scout. He was sent to the military factory 202 to ensure the smooth development of the "Blue Fish" nuclear submarine. At the same time, a group of evil foreign forces are eyeing the confidential drawings of nuclear submarines, and the spies they sent are also hiding in the 202 factory. In the 202 factory, Ma Dong met his good friend Chen Qiqian (Zhao Lixin) and the factory flower Feng Shuya (Zuo Xiaoqing). Chen Qiqian has been pursuing Feng Shuya, and as time goes by, Feng Shuya gradually falls in love with the honest and reliable Ma Dong. However, Ma Dong's special identity prevents him from confessing his feelings for Feng Shuya. In the misunderstanding, Feng Shuya married Chen Qiqian in anger. What she didn't know at this time was that Chen Qiqian was harmed by the recipient and had been forced to become a pawn of the enemy forces.