Carter has low expectations for his week-long summer stay at his grandmother's small-town Pennsylvania home. With few kids in the neighborhood, Carter resigns himself to a summer spent on the porch sipping iced-tea and losing himself in his tablet. When he sees his grandmother's polite, quiet neighbor Miss Fern, from the porch, he reminisces about the times when Miss Fern would tell him about her grandfather, Captain John Fern, a Civil War hero. As memories of this story wash through his mind, Carter suddenly finds himself transported through time to the thick of the War's action. Called into action as a drummer boy, he soon finds himself on the cusp of a greater adventure than he ever could have imagined.