In 1942, neutral Turkey is the battleground for spies and agents provocateur who are trying to win the country's support. Joe Barton, an American agent posing as a salesman, encounters a beautiful woman named Ana Remzi on the train from Ankara to Istanbul. Ana tells Joe that she is being followed by an informer and begs him to carry some securities across the border for her. In Ankara, Ana assumes she has eluded her pursuer and telephones Joe, asking him to meet her at her hotel and return her securities. In the meantime, Joe has opened the document that she gave him and discovered that instead of securities, it contains photographs of strategic areas in Turkey. When Joe arrives at Ana's hotel, he learns that she has been killed. Joe hides when another man enters the room and searches Ana's body. Joe then escapes out the back of the hotel, where he is seen by a woman waiting in the shadows. She is joined shortly by the man in Ana's room. Back at his own hotel, Joe is questioned by men claiming to be police, who take him to the home of Colonel Robinson, an agent provocateur working for the Nazis. Robinson offers to buy the photographs, and when Joe refuses to sell them, he turns him over to his men for torture. Joe is rescued by Nicolai Zaleshoff, the man who searched Ana's body. Nicolai's sister Tamara drives them to the Zaleshoff apartment, where Ivor Rashenko, the man who followed Ana from the train, is waiting. Nicolai explains that he and Tamara are Soviet agents who want the photographs in order to prevent Robinson from using them to convince the Turks that Russia plans to invade their country. Joe agrees to meet them at the Russian embassy and turn over the photographs, but when he returns to his hotel, he discovers that his room has been searched and the photographs taken. Joe now goes to a tobacco store to meet his contacts. With their help, he traces Rashenko and the Zaleshoffs to Istanbul. Robinson now has possession of the photographs and bribes the owner of a newspaper into printing them. Joe and his Turkish contact, Hassan, go after Robinson, who asks Joe to become a Nazi agent. Joe tentatively agrees and Robinson asks him, as proof of his loyalty, to shoot Nicolai. Realizing that the gun Robinson gives him is empty, Joe pulls the trigger, but Robinson has only been toying with him and is about to kill him when Joe breaks free. Nicolai is killed in the escape, but Joe gets to the newspaper in time to prevent the publication of the photographs. After Joe turns Robinson over to the Turkish police, he and Tamara move on to their next assignment in Cairo.