After committing an act of sabotage against the Nazis, Vincent Van Der Lyn escapes from the Netherlands to neutral Portugal. At the border, Lisbon police captain Pereira questions Vincent about his activities and warns him to honor the country's neutrality. During the questioning, Lutzke, a German, notices that Vincent's passport was not stamped by the Vichy French border patrol and follows Vincent to a café. Outside the café, a man named Du Val is shot, and Irene Duchatel, who was just speaking with him, rushes inside and sits at Vincent's table to escape the police. Vincent is attracted to the beautiful Irene and buys her a drink, but a short time later, she pretends to make a phone call and slips out the back door. Determined to find her again, Vincent goes to a casino she had mentioned in passing. At first Irene denies that they have met before, then she warns Vincent not to contact her again. Later, Irene is joined by Hugo Von Mohr, an official in the German embassy, and Lutzke, and Vincent contacts Riccardo Quintanilla, the head of the resistance movement in Lisbon. Du Val's death has upset the group as he was supposed to brief Jennings, the man who is to replace Vincent in the Netherlands. Quintanilla informs Vincent that the death also means there is a traitor in the organization. Vincent offers to meet with Jennings the following evening. In the morning, Vincent meets Irene, having learned where she lives, and takes her for a drive in the country. When he tells her that he has fallen in love with her and asks her to join him in England, she explains that Hugo saved her from a concentration camp and that he is her husband. On returning to his hotel, Vincent finds a badly wounded Jennings in his room. Before Jennings dies, he manages to tell Vincent that his killer "took the eagle." Within minutes, the police arrive, having received an anonymous tip, and arrest Vincent for Jennings' murder. When Irene learns of the arrest, she tries to give Vincent an alibi, but Vincent accuses her of setting a trap for him. Later, Vincent escapes from jail and hides in the home of a fisherman sympathetic to the resistance. Quintanilla dispatches Irene to bring Vincent a gun. She explains that she is also a member of the underground, as is Hugo, and conducts him to Quintanilla. There, Vincent proves his innocence when he delivers Jennings' message about the eagle. Secretly, Vincent and Quintanilla set a trap for the traitor, who is revealed to be Hugo. When Hugo tries to escape, Vincent kills him and finds the "eagle," a coin used for identification by the resistance, in his pocket. Pereira witnesses the killing, but allows Vincent to go free. Vincent agrees to take Jennings' place and return to the Netherlands, and Irene promises to wait for his return.