Instructor Lin who is home from training the imperial troops for several years. He meets his wife and runs into his brother who has become a monk at the local temple. His superior Lord Gao, strangely decides to rape Lin's wife in the temple but Lin interrupts the crime. His brother is enraged and tries to kill Gao but Lin stops him with the help of Lin's training brother and old friend Lu who works for Gao. Lin is loyal to the Commissioner and will not do anything to harm his son. Once back at the Commissioner's house, Gao and Lu hatch a plan to discredit and eventually kill Lin all with the Commissioner's approval. The plan is put into motion and Lin is unjustly arrested for trespassing on imperial property.

本片为程刚导演、辛汉白编剧，可谓早期的「监狱风云」。故事描述，香港在1953至1955年，曾被警方称为最黑暗的时期，那时候罪恶泛滥，百弊丛生，一日可发生三十二宗惊人案件，而犯罪份子有百分之四十是积犯；英廷特派专员来港调查监狱的措施，发现狱中不良份子，滥用权力，公报私仇，歪曲政府的监狱制度，造成犯人越变越黑，监狱变成地狱。影片主角江才（刘永）因不甘受探长侮辱，结果被控妨碍公务，判刑一年零八个月……