一起去吃拉面吗？

　　Robbins is sentenced to prison for the assassination of his general officer, a prison you leave only when you die. Since nobody ever leaves the prison, nobody knows what the prison is like. The prison manager realizes this and buys himself an island playground called "Absolom," where the worst prisoners are free to create an isolated barbaric society, and where the strongest men rule...a living hell. Robbins is sent to Absolom after he almost kills the prison manager.

 由于两年前揭发同僚贪污，台北警官黄火土（梁家辉）被上级报复调入冷门的外事组工作，利益也曾连带受损的新同事对他怒言相向，加上妻子清芳（刘若英）受不了他长期不回家要求离婚，黄火土感觉他的世界正在逐渐四分五裂。就在此时，三宗受害者的身份并无关联的震惊了台湾社会的离奇命案发生，法医（杨贵媚）验尸发现他们都是因中一种神秘的黑霉菌产生幻觉而死，因为缺乏此方面的人才，当局从美国请来此种案例的侦办专家凯文莱特（David Morse）协助破案，黄火土重被任用。随着一桩令所有人都目瞪口呆的事实的被发现，一场围绕政治利益与民众利益的斗争也在黄火土和办案伙伴李丰博（戴立忍）及整个警察队伍之间展开。

一对情侣取消婚礼后，这个吝啬的男子试图要回他赠送的吐司机，却无意中卷入谋杀案。