Liu Yue Ping reports to the ICAC about a rich 2G Cao Yuen Yuen who bribed officers of the Hong Kong Correctional Services (HKCS) from inside the prison. William Luk decides to infiltrate the prison as an inmate to conduct his investigation, while his partner Ching Tak Ming and Chief Inspector Lau Po-keung back him up from the outside.

Genre: Action, Crime