Lieutenant Bert Hall, an ace American flyer serving in World War I as a member of the French Lafayette Escadrille, is wounded in an aerial battle and forced to land behind enemy lines. Finding his German opponent dead, Hall exchanges uniforms with him and is taken to a German hospital to recover. There he meets his old Kentucky sweetheart, who was unable to escape Berlin when the war broke out. Accompanied by the Countess of Moravia, who claims sympathy with the Allied cause but is actually a German spy, they escape to France in a German plane. Through the countess' duplicity, Hall is accused of betraying the French government and sentenced to be shot, but his American lover uncovers evidence that saves him at the last moment.