Single mother Lin Xiaoqing, in order to save her critically ill daughter, asks her ex-husband Duan Hu for life-saving surgery fees, only to be ruthlessly humiliated by him and his new lover Ke'er. Duan Hu, who values boys over girls, regards his daughter as a burden, is obsessed with having a 'unicorn son,' and makes a clean break with heartless cruelty. Driven to desperation, Lin Xiaoqing relies on evidence of Duan Hu's illegal activities retained from early years, unites with a senior from the legal circle to set a legal trap, sends Duan Hu—who is suspected of economic crimes—to prison through legal means, takes back her daughter's treatment fees, and finally protects her daughter's rebirth, walking out of the darkness.