Lao San, is a retired Marine veteran who lives in his world of innocence and optimism due to a brain injury. He assumes the role of a dedicated vigilante and fights people whom he considers bad.
After accidentally killing his competition during a kung fu movie audition, Cheng Lindong is sentenced to seven years in prison, upon which he is released back into the world and the arms of his faithful girlfriend, Ke Lin. In a desperate move for a new life, he changes his identity and finds a job...