A large caravan of settlers attempt to cross the Oregon Trail. Breck Coleman (John Wayne) is a young trapper who just got back to Missouri from his travels near Santa Fe, seeking to avenge the death of an old trapper friend who was killed the winter before along the Santa Fe Trail for his furs, by Red Flack (Tyrone Power, Sr.) and his minion Lopez (Charles Stevens (actor)). At a large trading post owned by a man named Wellmore, Coleman sees Flack and suspects him right away as being one of the killers. Flack likewise suspects Coleman as being somebody who knows too much about the killing. Coleman is asked by a large group of settlers to scout their caravan west, and declines, until he learns that Flack and Lopez were just hired by Wellmore to boss a bull train along the as-yet-unblazed Oregon Trail to a trading post in northern Oregon Territory (which at the time extended into current British Columbia), owned by another Missouri fur trader. Coleman agrees to scout for the train, so he can keep an eye on the villains and kill them as soon as they reach their destination. The caravan of settlers in their Covered wagons would follow Wellmore's ox-drawn train of Conestoga Wagons, as the first major group of settlers to move west on the Oregon Trail. The film is set somewhere between 1837 and 1845.<ref group="notes">Ruth tells Honey Girl that there are 26 stars in the flag, dating the movie between Jan., 1837 and March 1845.</ref> This is historically accurate, as the first major wave of settlers on the Oregon Trail was in 1843, although the details were completely different.