Young and promising advertising designer Lu Jiayao (played by Tony Leung) accidentally injured someone while trying to stop bad elements from provoking trouble and was sentenced to three years in prison. In prison, he offended the gang boss because of his honest personality and was bullied. The old prisoner Zhong Tianzheng (played by Chow Yun-fat) couldn't bear it and helped him out. The two became friends in need. Zhong Tianzheng originally had a complete family, but he accidentally killed his wife because of his gambling addiction. When he was imprisoned, he regretted his past and decided to walk out of the high walls and start a new life. However, because he stood up for Lu Jiayao, he offended the ruthless warden (played by Cheung Yaoyang) who was bullying and ruthless. Since then, he was involved in the vortex of evil forces in prison. When he was desperate, he gave up the philosophy of "enduring if you can" and decided to use violence to fight violence.