Rory O'Manion is a hot-headed and rebellious farmer, who has become increasingly fed up with his meager existence in British-controlled Ireland during the Great Potato Famine of the 19th century. He ironically meets and falls in love with Rachel Clement, the feisty daughter of a local English landlord, but he decides to set off to establish a new life in America without her. Once there, after working various day labor jobs, his bravery and determination help to earn him a full-time job and later, a business partnership in a gunpowder mill that Rachel's uncle owns in Philadelphia. Rachel's subsequent arrival in America reunites them, setting off a chain of events where the two families grow increasingly intertwined on both sides of the Atlantic, during the turbulent decades of pre- and post-Civil War United States and the Industrial Revolution.