I only read the summary I found online.
Mr. Chiu Muguang is a professor who has a strict moral code. He knew that what the police officer did to him was rude and wrong. Thus, he lodge a complaint to report the officer's behavior. Because of this, Mr. Muguang was falsely accused of disturbing the peace and of sabotage.
Despite being locked up in jail, Mr. Muguang has been very vocal about his innocence and he only backed down and admitted the accusation when his student was also thrown in jail. In the end, even though Mr. Muguang was false accused of being a saboteur, he made the accusation true when he infected the people eating in the restaurants near the police station with acute hepatitis.