The story of Shanghai Fortress takes place in the year 2035. The extraterrestrial dark forces attack the earth and try to capture the energy treasures, which human beings rely on. The four Fortress Cities, where energy treasures are located and protective shields are built, have been badly hit.
An international joint force, UNDC, is established by elites from all over the world to defend against the annihilators' attack. With the fall of New York, Tokyo, and New Delhi, Shanghai Fortress becomes the last hope and safe haven of mankind.
Fresh out of college graduate Yang Jiang (played by Han Lu) falls in love with senior UNDC Chief Commander Lan Lin (played by Qi Shu) at first sight and follows her serving as a reservist in Shanghai Fortress division. Yang Jiang falls in love with Lan Lin but never has a chance to express his secret crush on her.
Soon after joining UNDC, Yang Jiang meets Hantian Pan, Yu Zeng and Yiyi Lu in the workplace. During initial training, the four become close friends and later participate in the UNDC elite team, "Grey Eagle", taking up the dangerous final mission to fight back against the alien invasion.
As the annihilators changes their attack patterns, it becomes harder for UNDC to stabilize the city's protective shield. Under fierce attacks and sacrifice of countless teammates, Yang Jiang puts his romantic feelings for Lan Lin aside and grows up into a brave soldier carrying tremendous amount of courage to fight the dark forces, defend Shanghai and save humanity...