在这部第三人悬疑/惊悚/黑色电影片中,二战后，美国作家马丁（约瑟夫•科顿 Joseph Cotten 饰）应好友哈里（奥逊•威尔斯 Orson Welles 饰）邀请到维也纳工作，岂料刚到达目的地就传来了哈里车祸身亡的消息。哈里葬礼上，马丁遇到了当地军官卡洛维，卡洛维很不客气的请他马上离开维也纳。马丁没有理会，决心留下调查出好友死亡的真相。
马丁找到哈里的女友斯科姆特小姐（阿莉达•瓦莉 Alida Valli 饰）一起调查事件的真相。随着调查的深入，他们发现内幕越加扑朔迷离，首先是他们的房东遇害，接着马丁自己发现被人跟踪，而且他查出哈里死的时候还有个第三人在场。于是，一切关键就在于找出这个神秘的第三人。
An out of work pulp fiction novelist, Holly Martins, arrives in a post war Vienna divided into sectors by the victorious allies, and where a shortage of supplies has lead to a flourishing black market. He arrives at the invitation of an ex-school friend, Harry Lime, who has offered him a job, only to discover that Lime has recently died in a peculiar traffic accident. From talking to Lime's friends and associates Martins soon notices that some of the stories are inconsistent, and determines to discover what really happened to Harry Lime.
文明的地下。利益与情感下挣扎的个人抉择。黑色电影的经典。拍出了钱德勒侦探小说的感觉。《第三人》观影预习。从史上最拉风进场说起。摩天轮上的那段台词。一部英国电影，两个美国人。导演说。曼尼·法伯论《第三人》：衰颓的诗意【译】。
