In Chicago, where shootings are frequent, Paul was originally a gentle, kind and skillful doctor with a happy family. A sudden misfortune caused his wife and daughter to be bullied by thugs, his daughter fell into a coma, and his beloved wife lost her life, leaving him forever. However, a series of murders in the city left the police helpless. For various reasons, Paul's case could not be closed, and the murderer who should have been punished was at large. In collapse and despair, Paul's life values changed completely. In order to avenge his family, Paul decided to find the murderer alone, take the initiative, and punish violent crimes on the streets of the city alone. The police and the public had different opinions and endless debates about this mysterious "hooded man" who was upholding justice. Under the guise of a "guardian angel", Paul finally faced a life-and-death battle with his enemies.