In 1847, Caleb "Mac" McDougall, a young Bostonian, seeks adventure on the Oregon Trail. As he passes through Missouri, he rescues Jenny Calhoun, a lonely girl in trouble. To join a wagon train bound for Oregon, Mac and Jenny pose as a married couple. On the arduous six-month trek, they confront raging rivers, rugged mountains, and untrustworthy companions. Together, Mac and Jenny face the best and worst in themselves and in each other, while discovering the beauty and danger of the western frontier.