夏威夷念大学的香港富豪子弟李泽星(周星驰 饰)学业无成挥金如土,是校园一霸,终因搭上黑帮老大情妇遭黑帮追杀,身体被炸成碎片。 在李泽星父亲(吴孟达 饰)的请求下,教授(徐锦江 饰)将李泽星全身人造复原,并把最新研制成功的无敌芯片置入其身,令其摇身一变成为无敌“百变金刚”。黑帮老大得知李泽星复活后,将写有战争程序的芯片植入手下身体,令其变身“铁甲威龙”前来追杀李泽星。为赢得暗恋的女同学虫虫(梁咏琪 饰)的芳心,李泽星决意重塑形象,奋力与“铁甲威龙”展开大战。Stephen Chow plays a rich playboy who is blown up by a mafia boss when he flirts with the boss's girl. Through a series of circumstances his professor makes him a synthetic (robotic) body that allows him to change into a variety of "Mrs. Wong's Household products" like a microwave and toothpaste. Chow eventually goes to work at a school notorious for it's rowdy students and singlehandledly disciplines them all. He then goes on to marry a former classmate played by Gigi Leung. But before the wedding happens, the mafia boss finds out that Chow is still alive and sends in his own human-robot to take Chow out for once and for all.