The narrative follows a series of frontier episodes centered on a timber-built fort besieged by a Sioux war party led by Oak Heart, whose daughter White Antelope exerts influence among the warriors. Inside the stockade Major Baldwin and his garrison face dwindling food, water, and ammunition and debate sending a rider through the surrounding rifle-armed lines to fetch relief. The story alternates scenes of desperate defense and bold sorties, with cavalry detachments under officers like Dick Danforth and Captain Keyes breaking through encircling forces, and scouts such as Cody taking daring actions to intercept enemy movements, while the broader spectacle of frontier showmanship and conflict underpins the action.