Lieut. Robert Banks, an American aviator on leave in Paris, meets Mary Gordon, a young American who lives abroad, but their romance is cut short by his return to the front. In an air battle, Robert brings down and captures the Grey Eagle, Baden, and takes him to American Intelligence in Paris. Mary, ostensibly a spy for the Germans, drugs Robert, who awakens to find that his uniform has been stolen by Baden. Later, in an exciting air conflict, Baden is wounded but shoots down Robert's plane. The German rescues him, however, and takes him to an Allied hospital, assuring him of Mary's love; his faith in her is restored when he learns that she is actually a spy for U. S. Intelligence..