Zhao Lin, a street beggar, is mistaken for the younger brother of a mentally challenged woman who insists on calling him her little brother. He tries repeatedly to shake her off, but she always manages to find him again. At first, Zhao Lin finds her nothing but a nuisance. However, his silly big sister treats him with unwavering sincerity and even risks her life to protect him in times of danger. Gradually, her kindness melts Zhao Lin's cold heart, and he begins treating her as his own family, caring for her devotedly. Determined to change their fate, Zhao Lin works hard to help his big sister regain her sanity. Together, they support one another, struggle to build a better life, and finally escape their miserable existence as beggars, carving out a future of their own and demonstrating the power of perseverance and determination in the face of adversity.