During the US civil war, Elinor, a pretty northern girl, comes south to visit her aunt. Little does anyone know, but she's a spy. Lt. Yancey, who's close to being engaged to the fetching and resourceful Rose, is gallant enough to show the Yankee guest around, including a walk down a hidden creek where a gunboat is built and awaits powder. Elinor sends this intelligence north, and the Blue Coats attack.