龚少爷（谢霆锋饰演）有一个好哥们名叫老巴（张家辉饰演）两人功夫高强且侦探推理能力都很强两人的愿望就是当上捕快能去断案，好不容易机会来了，可也只是一个实习捕快，每天无所事事，除了打扫一些杂物就是像下人一样被人随意指挥。两人正发愁暗无天日的时候，翻转命运的机会来了，城中有一个张员外家里图遭变故，上下十几口人全部被杀，而家中的玉观音下落不明。龚少爷这才有机会来到现场一起勘察，结果他发现了诸多线索上报给了不透铁无情，铁无情虽然相信龚少爷的推测，但却被人栽赃陷害下了大狱

火龙女、火龙女此时也在牢房中，见到了被灌进来的老巴和龚少爷，双方商议之后不能坐以待毙，一起自救硬闯出了大牢，为了自证清白，查找玉观音的下落，四个人结伴一起沿着线索查找，不知不觉来到了财神客栈。

Master Gong (played by Nicholas Tse) has a good buddy named Lao Ba (played by Zhang Jiahui). My only wish is to become a police officer and solve cases. Finally, the opportunity came, but I was just an intern police officer who had nothing to do every day except cleaning up some sundries and being ordered at will like a servant. When the two were worrying about the dark days, the opportunity to reverse their fate came. There was an accident in the house of Zhang Yuanwai in the city, and all the members of the family were killed, and the whereabouts of Yuguanyin in the family was unknown. Only then did Young Master Gong have the opportunity to come to the scene to investigate together. As a result, he found many clues and reported them to Tie Wuqing. Although Tie Wuqing believed in Young Master Gong's speculation, he was framed and sent to prison

Fire Dragon Girl and Fire Dragon Girl are also in the cell at this time, seeing the old bus and Young Master Gong who were poured in, after the two parties discussed Unable to sit still, they rescued themselves and broke out of the prison together. In order to prove their innocence and find out the whereabouts of Yu Guanyin, the four of them searched together along the clues and came to the God of Wealth Inn unknowingly.