高正辉（方中信 饰）乃警方卧底，为掩饰身份而混入黑社会，但常被其父所责骂。其父因得悉程立山（龙方 饰）之犯罪勾当而被杀害，辉往祭父时与亲妹高智玲反目。辉为了爱人Lisa（叶晨 饰）与妹妹着想决心抽身退出江湖，但遭上司否决。辉借机与程手下阮文混熟，二人往与大圈仔交易时遭伏击，又被智玲率警员追捕，辉乘机向阮文教唆杀程，但阮文下手…

Captain Drummond and his girlfriend want to marry but a hidden treasure in the house in which they want to celebrate their marriage is complicating the situation.