A young man from a Kuomintang military family experiences a life-changing journey in Shanghai, leading him to embrace Communist ideals and become a skilled undercover agent, depicting a generation's pursuit of faith and purpose during turbulent times.

Detective Song Cheng discovers a link between a current case and an unsolved crime from four years ago, both tied to key witness Yu Xiao. As he digs deeper, Yu Xiao’s hidden past comes to light. She joins the investigation with Song Cheng’s support, but mounting obstacles threaten their pursuit of the truth. Together, they fight to uncover the real culprit and bring justice to light.

The movie tells the story of Bai Sheng (by Deng Chao), a veteran employee of an Internet company who is forced into a workplace fiasco and decides to join forces with others to break the ice in order to defend his rights, only to be caught up in an even bigger whirlpool of mystery.