Sixteen-year-old twins Susanne and Stephen leave their Gettysburg farm, one as a nurse and the other as a Union soldier, little knowing that their hometown will soon become the focus of the Civil War.

Life in Philadelphia after America's declaration of independence is very exciting for Barbara Lyman and Patsy Black. British spies could be anywhere, even in Barbara's stables. When her father offers shelter to two travelers, Barbara suspects they're up to no good and does some spying of her own. She discovers they are British soldiers, but before she can go for help, they steal the wagon she's hiding in, and Barbara must figure out a way to escape...