In Vienna, in the beginning of the Twentieth Century, Captain Karl von Raden and his partner Captain Max Heinrich learn in the box office that the ticket for the opera is sold-out. Out of the blue, a man returns his ticket and Karl buys it and shares a box with a gorgeous woman that is waiting for her cousin. Karl gives a ride home to the lady and they spend the night together. On the next day, they spend a wonderful day in the countryside together. Karl is assigned to travel to Berlin by train to deliver secret plans to the German government. His uncle, Colonel Eric von Raden, who is the chief of the Austrian secret service, advises Karl the woman with whom he had spent the previous day is the notorious Russian spy Tania Fedorova. While in the train, Tania meets Karl to tell that she is in love with him, but he rejects her telling that he knows who she is. On the next morning, Karl wakes up and finds that the plans have been stolen and he receives a message from Tania telling that she came as a woman in love with him and left as his enemy. Karl is expelled and imprisoned by the army as traitor but his uncle offers him the chance to clean his name, traveling to Warsaw to find who the traitor is. Karl poses as pianist and meets Tania and her lover, the powerful General Boris Alexandroff. What will Karl and Tania do? 打动人心的表情。 一次偶然中，青年军官卡尔（康拉德·纳格尔 Conrad Nagel 饰）邂逅了美丽的女子塔尼亚（葛丽泰·嘉宝 Greta Garbo 饰）。塔尼亚的风韵和神秘深深的吸引了卡尔的注意，令他深陷情网之中无法自拔。之后，卡尔前往柏林执行任务，在此期间意外的得知塔尼亚的真实身份竟然是正在遭到通缉的俄国间谍。 很快，卡尔就因为泄露了情报而遭到了逮捕，只有他的好友埃里克（爱德华·康奈利 Edward Connelly 饰）知道他是无辜的。在埃里克的帮助下，卡尔越狱前往华沙寻找塔尼亚，这个世界上只有塔尼亚一人能够还他清白。实际上，塔尼亚早就已经厌倦了整天提心吊胆的双重生活，而且她也深深的爱着卡尔。
