Lo Ka Yiu, a young ad designer who is sentenced to jail for manslaughter, has gotten himself in trouble with the corrupted wardens and fellow inmates of Triad background. Chung Tin Ching, a veteran inmate and Yiu's mentor, is forced to confront his comrade's enemies time and again, leading up to the final showdown with the head of security.

Ching is a prisoner in a Hong Kong jail that has a large population of Mainland Chinese prisoners. Ching escapes to see his young son, who he has been put in an orphanage. He surrenders himself to authorities, but the vengeful chief of security, Zau, arranges for Ching to be set up in the eyes of the Mainland gang.

In this latest chapter of the PRISON ON FIRE saga, Fung, a gang leader sentenced to life imprisonment, gradually turns to religion. With the help of the prison's priest, Fung begins to preach to his fellow cellmates. But the toughest skeptic turns out to be his own son, who is now in the same prison.