A young girl from the North staying with her grandmother on a Maryland farm during the Civil War forms a close but occasionally strained friendship with a neighboring older girl and learns how sectional loyalties shape daily life. The story follows her countryside play and household routines, encounters with soldiers of both sides, moments of fear and courage, a brief capture, and a hurried journey to Sharpsburg, culminating in the tense experience of the Antietam battle and its immediate effects on local families and children.