千禧年前后,虎城动荡不安,政府为了重振秩序,降低犯罪率,决定铲除腐败的地下娱乐业和洗黑钱的行径。以四爷(张兆辉 饰)为代表的黑恶势力及商业调查厅厅长左君哲(吴镇宇 饰)暗中操控局势,试图趁市场开放之机浑水摸鱼争夺经营权。以江文峰(钟汉良 饰)为代表的警方与他们展开了一场惊心动魄的对决。The government decides to restore order to Tiger City, but underworld forces and the Commercial Investigation Department are trying to take advantage of the market and vie for business rights which leads to a thrilling duel with the police