黄蝴蝶(邵美琪 饰)是一个失意的编剧,几经波折,已经堕落到向闺蜜阿娟(毛舜筠 饰)探讨三级片的程度。胡蝶的邻居警官吕奇(梁家辉 饰)对她颇有好感,后者在英雄救美后意外得到了她家的钥匙,然而他的不请自来,却落得狼狈而逃。因为事业接连遭受重创,胡蝶决定在江边横刀自尽,然而怯懦 的她终于没有自裁,反而盲打误撞惊扰了一对偷情的鸳鸯。后者仓皇逃窜,却遗留了一些私人财物。为了物归原主,胡蝶和阿娟一同登门,却无意中卷入了一场黑吃黑的血案。侥幸逃生的胡蝶临走前,还多事地留下了黑玫瑰的字条,而阿娟却因为留下了手印而被警方对号入座。结果,黑玫瑰成为了全城热议的话题,而这也引起了黑玫瑰掌门人(冯宝宝 饰)与师姐(黄韵诗 饰)的注意,于是一场剪不断理还乱的情场争夺战开始上演了……The film is about a movie hero of the 60s called Black Rose, but she was actually real, and a woman in the 90s is mistaken for her because she's in the wrong place at the wrong time and somebody is doing crimes as Black Rose, who isn't the real Black Rose