Hong Kong nihilism. December 22, a street quarrel leads to the death of a gang leader’s son. Next day, he seeks revenge on his brother, a rival boss. He calls on Liu, a fixer, to import a hit man from the mainland. Lai Fu, a tough and youthful hick, arrives with a day pass. The cops, led by the morose Milo, hear about the killer; they open a full-scale Christmas Eve operation to find the warring brothers and Lai Fu. Lai Fu rescues a hooker, Dan Dan, from a sadist and asks her to help him find his way around Mongkok. By nightfall, Liu has double crossed Lai Fu, the brothers are hiding, the cops are everywhere, and Lai Fu and Dan Dan are on the run. Peace on earth, good will to all?
In this prequel to Mou gaan dou (2002), Chan Wing Yan has just become an undercover cop in the triads while Lau Kin Ming joins the police force. Both the triads and the police find an enemy in a rival crime boss.
Chui Chik tries to lead a quiet life as a librarian. However, he is really a former test subject for a highly secretive supersoldier project and the instructor of a special commando unit dubbed “701.” The 701 squad is used for many government missions, but after one of the agents kills a team of policemen in an uncontrollable rage, the government decides to abort the project and eliminate all the subjects. Chui Chik helped the surviving 701 agents flee the extermination attempt. Having escaped, Chui Chik went separate ways from his team. Later, he discovers that the rest of the team were responsible for a violent crime spree that was beyond the capability of the local police. He sets out to stop them, donning a disguise and using the superhero alias of “Black Mask”. Having lost the ability to feel pain due to the surgery performed on the super-soldiers by the military, Black Mask is almost invulnerable.