In 1959, Yau Ma Tei foreign detective Reeve retires, leading to a competition between bitter rivals Lee Rock (Andy Lau) and Ngan Tung (Paul Chun) for the position. Although Ngan ultimately gets the position, Lee is promoted to Chief Chinese Detective, a position that supersedes Ngan in seniority. After Lee takes office, he reforms each department, gaining support from many businessmen and his momentum rises while Ngan's standing plummets, fueling his hatred towards Lee. He hires a henchman from mobster King Crab (Michael Chan) in a failed assassination ploy against Lee. Fearing he will be discovered, Ngan has Crab killed. Lee continues to consolidate power and throughout the 1960s, gains complete control of the entire Hong Kong Police Force and its operations whilst actively investing in commercial real estate, entertainment and many other fields. He comes to amass an estimated wealth of HK$500 million.<br /><br /><br />故事承接上部，前面几分钟简要回顾了上部的一些主要情节。<br /><br />1959年，油尖區的英籍探长「祁利夫」退休，此肥缺引起雷洛（劉德華飾）与颜同（秦沛飾）的争夺。颜同不惜勾结全香港各大捞家甚至毒枭，籌得三百萬元，大買人頭，务求登上宝座。並且向老虎蟹（陳惠敏飾）承諾將把油麻地避風塘改為運毒卸貨碼頭，不用再從新界上岸被抽成。<br /><br />雷洛從豬油仔（吳孟達飾）口中得知顏同的計畫後，一度陷入困境。透過岳父（田俊飾）的指點，从奉承警务处處长好赌的夫人身上下手，也因此得到处长对雷洛的器重。最终颜同虽然得到油麻地探长的位置，但是雷洛却被提拔为新设的总华探长之职，居于颜同之上。<br /><br />雷洛得知舊情人阿霞（邱淑貞飾）身边的7岁小男孩是他的儿子后，就安排了一个住处给他们母子俩并时常探望之。妻子阿嫦（張敏飾）知道阿霞母子的处境后，同意雷洛娶阿霞当側室，可正当阿霞准备结婚时，香港政府废除了允许納妾的大清律例。阿霞与阿嫦见过面后，她搬离了住处并给雷洛留下了一封告别信，以及雷洛当初送给她的定情玉坠和一件自己穿过的衣服。雷洛发现阿霞母子离开后倍感惆怅。
