Following a completely unnecessary introduction about the US Civil War (unless you know NOTHING about it), the story begins late in the conflict. It seems the Union want a volunteer to go on what is likely a suicide mission...to pretend to be a spy and get captured in order to give false plans to the Confederates. After Captain Braydon (Gary Cooper) catches his fiancee with another man, he volunteers for this suicide mission.
What made this movie just awful to me wasn't Cooper....he was his usual excellent and restrained self. But the Southerners in the film almost seemed like parodies of Southerners...with outrageously exaggerated accents and manners. While it might have played fine in 1930, when seen today it might just elicit laughter...it's that bad and overdone when combined with the occasionally terrible dialog. So my advice is that if you see this forgettable film, try to pay attention to Cooper...and ignore most everyone else.