程家三兄弟为民除害,因此而惹恼了地煞(权永文 饰)和天煞(任世冠 饰),遭到两人报复。老大惨死于屠刀之下,老二程振南(田俊 饰)和老三程振北(陈慧楼 饰)分别带着他们的儿子阿龙(成龙 饰)和阿栋(惠天赐 饰)踏上逃亡的旅程,一场混乱之中,阿龙和阿栋失散,从此踏上了两条截然不同的人生道路。 时光荏苒,阿龙成长为了乐观开朗的正直青年,一次无意中,他使出了失传已久的程家拳,被一直耿耿于怀的地煞和天煞发现了行踪,结果家中惨遭灭门,丐帮帮主的女儿小玲(林银珠 饰)帮助阿龙逃过一劫之后亦不幸命丧黄泉。此仇不报非君子,阿龙和久违的阿栋决定联手,替父亲等人报仇。A pair of evil gung-fu artists, Heaven and Earth, are slaughtering the entire Yin-Yang brotherhood. he movie opens with two members of the brotherhood and their two male children being chased by Heaven, Earth, and misc. bad guys. The two members get away separately with their children. Twenty years later we see Jackie Chan as he hunts frogs and snakes and keeps them in his pants. You learn he was one of the boys; the other is a lazy man who uses windmill-driven levers to deliver things to and from bedside, even a chamberpot and breakfast. Eventually, their respective paternal figures are killed, and they are forced to fight Heaven and Earth.