Laughing is judged guilty of murdering gang lord Michael So and is sentenced to life imprisonment. Locked up behind bars, he meets the seemingly benign inmate Fok Tin Yam, a university professor in criminal psychology who is jailed for drug possession. Highly intelligent and manipulative, Fok reveals the power of his mind games by effortlessly subduing the violent prison bully. He also deduces that Laughing is sent to the prison on an undercover mission to find out the rogue cops within the police force. The clues lead him to inmate Chit, a former sergeant from the Narcotics Bureau who has been suffering from a mental disorder. To unlock the critical information from the deranged man, Laughing must get the help of Fok, but this enigmatic figure has an agenda of his own…
Sit Ho Ching used to be an everyday white-collar worker who had no ambition and no plans for his future. Everything went smoothly until one day, when his boss set him up and his girlfriend cheated on him, he suddenly became a jobless single man, which made him rethink his past life of duties and routines. From then on, he decides to pursue wealth and fame by all means.
Realising that he will be defeated in no time during a police showdown, a thug shoots himself to force the cops to cease fire and take him to the hospital. In the hospital, he claims human rights to refuse immediate treatment in order to buy time for his underlings to rescue him. The detective in charge sees through his scheme but decides to play along so as to capture his whole gang once and for all.