Nate and Walt MacGregor are cousins who have never met, living on opposite sides of a deeply divided continent. Nate, the privileged son of a plantation owner in the American South, and Walt, an abolitionist son of a pioneer farmer in Canada West, are both profoundly affected by the story of a runaway slave named Sunday. While Nate prepares to fight for his Southern homeland, Walt fears that the seizure of a Confederate ship with British envoys on board will pull Britain into the war. When the cousins at last cross paths during the Battle of Shiloh, they learn that what unites them is more powerful than what divides them.