A money laundering scheme was uncovered inside a Hong Kong investment bank. The money vanishes and the international mob boss "Big Bob" demands the bank to return all of the money. First she starts with assistant chief officer Connie. In order to protect Connie, Connie's boyfriend and bank chairman Billy ask for "hired guns" from retired mob boss Uncle Ghost. Uncle Ghost sends his followers Nick, Big Brother, Ah Fei and female bodyguard Lisa to protect Connie. But where did the money go?

任慕英（梁家辉 饰）是一个单亲爸爸，以教授钢琴来抚养女儿Ellen（蔡卓妍 饰）长大。可是女儿升上Band 5后就变得越来越不听话，令任慕英十分担心。Ellen一直觉得爸爸十分“娘娘腔”，觉得自己就算有什么麻烦，爸爸也是不可靠的人。Ellen的同学都误会了她的爸爸是个江湖高手——慕夜飞鹰，相继要求拜为师傅，此时Ellen才对爸爸改观。但任慕英被误以为是绝招的身手，不过是在照顾女儿的时候练出来的。
女儿开始觉得爸爸老了，可她还是到处惹祸，更被慕夜飞鹰的仇家胁持，任慕英为了救回女儿，独自女儿被困的地方……