Retired mercenary Chu Jing suffers from combat PTSD and chooses a quiet life to protect Niu Niu, the daughter of her fallen captain. Her upstairs neighbor repeatedly harasses her, deliberately triggers her condition, spreads rumors that she is mentally ill, and incites neighbors to isolate them, even harming Niu Niu and trying to take the child away. Pushed to the limit, Chu Jing reveals her mercenary skills, fights back decisively, exposes all lies, and intimidates the hostile neighbor. In the end, she reconciles with her trauma and peacefully protects Niu Niu.
