On holidays in Hong Kong, Mrs Ma gives birth to identical twins. A criminal in the same hospital attempts to escape, taking one of the twins hostage. The child is lost during the confusion, and Mr and Mrs Ma return to New York with one child. Years later, John Ma is a famous conductor and pianist, unaware that his twin brother "Boomer" is a mechanic/race car driver/bodyguard in Hong Kong. When John travels to Hong Kong to give a concert, the twins get caught up in each other's business, about which they are anything but experts. 商业功力与年轻的阿修罗。互换身份的体验。语录。多年后还是再看还是那么好笑。。。。绝地双尊和双龙会！。玩命×马友。导演会。张曼玉留给你们 我是来看利智的。重复看的次数较多的成龙影片。“双龙会”的“双胞胎”式魅力。 由于匪徒劫持，一对双胞兄弟刚出生即遭分离。弟弟玩命（成龙）被舞女捡到抚养长大，终日浪迹于社会底层，为帮朋友泡妞，他结识了歌女芭芭拉（张曼玉），因此得罪黑社会；哥哥马友（成龙）被一对有钱夫妇带去美国，接受了良好教育长为著名音乐家，回港开音乐会时，结识世伯家的女儿唐心（利智）。 阴差阳错中，两人互换角色进入对方生活，由于大家分不清谁是马友谁又是玩命，笑话迭出，芭芭拉与唐心的心思也渐起变化。音乐会上，玩命胡指乱挥不想大获成功，而马友在黑帮威逼下，开车去救被黑帮抓做人质的玩命的好友泰山，随后，两兄弟开始连手共斗强敌。
