One day he delivers food to the Swan Lake dance school, where he sees that Yan-Yan, the girl of his dreams, has broken her shoelace so he gives her the string that holds up his pants.
Overhearing his troubles, the woman to whom he regularly delivers food invites him inside, changing disguises from Yan-Yan to Hung Nam and finally revealing herself as the legendary Black Rose, a Robin Hood-like figure who helps the people of Hong Kong.
In order to defeat Black Rose, Lui Kei teaches Chi-Mo kung fu by making him perform all of the housework.
Black Rose eventually decides that she will work with Lui Kei to rescue Yan-Yan and they fight Sandra and her gang with a variety of unusual gadgets.
Black Rose feels the effects of her asthma and they are forced to flee, ending up on stage in a club where they must perform a musical number.
However, Tony Leung Kar-fai's goofy Lui Kei caricature is sorely missed, and the various send-ups (including the Japanese hit Shall We Dance?)
A handful of chuckles emerge (thanks mainly to Black Rose's inept weapons, like 'Killer Lipstick' and a lethal electrified pen that has to be plugged in to work) but not nearly enough to justify a viewing.