At the outbreak of the Civil War, Nathaniel Curry is a fifteen-year-old telegraph operator in Richmond. Entirely by accident, he helps direct Union artillery fire on a Confederate battery from a balloon, the first real use of an aircraft in warfare. A pariah back in Virginia, he flees to the North and joins the nascent Union Balloon Corps. The Corps, nearly forgotten today, revolutionized warfare, observing Rebel forces and communicating with the ground, and with Washington, by telegraph. The unruly aeronauts, however, are never embraced by the Army. Nathaniel, for his part, is suspected of being a spy by both sides even as he resists being recruited as a spy. Even his sweetheart, the daughter of a Confederate officer, turns against him. His last friend is Abraham Lincoln - and Lincoln wants him to do something he abhors.