Tsui Chik (or Simon in the US version) 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. Tsui Chik helped the surviving 701 agents flee the extermination attempt. Having escaped, Tsui Chik went separate ways from his team and lived in Hong Kong. Later at night 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 get rid of them, donning a mask and hat using the superhero alias of The 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.