Set in 1920's Shanghai, Chen Zhen (Donnie Yen), a local resistance fighter had been taken dead after a bloody skimmish to revenge his master's death.

After 7 years, he returns in disguise as Koo and befriends Casablanca boss, Mr Lau (Anthony Wong) and a girl named Kiki (Shu Qi) who is the club's famous courtesan.

Transforming into a caped fighter at night, Chen intends to uncover a plot linking the triads and the Japanese.