An explorer leads the way west for 19th-century settlers along the American frontier.

In the rugged northern Rocky Mountains of the 1830s, mountain man and fur trapper Flint Mitchell is planning a hunting trek into the beaver-rich Blackhawk Territory, despite protests from his Indian friend, Brecan, who tells him that the land belongs to Indians. After narrowly escaping an attack by Ironshirt, a young Indian war chief, Flint finds himself imperiled by a pack of wolves. He is rescued by Pierre, a French Canadian fur trapper, and Captain Humberstone Lyon, a bumbling Scottish hunter who fought in the Battle of Waterloo. While Pierre and Humberstone decide to join Flint on the dangerous expedition into Blackfoot territory, Flint, hoping to ensure the group's safe passage, buys and marries Kamiah, the granddaughter of Blackfoot chief Bear Ghost. Though he marries Kamiah for reasons other than love, Flint eventually becomes smitten with her. Kamiah successfully guides Flint and his men on their trek through rough terrain and crippling snow drifts and finally delivers them to beaver country. As Flint and Kamiah's marriage takes an unexpected romantic turn, Flint and Bear Ghost become good friends. Bear Ghost keeps the warring Ironshirt from harming Flint and his men, but tragedy strikes when Roy DuNord, one of Flint's men, kills Bear Ghost to avenge his brother's death at the hands of Indians. Brecan then kills Roy, and Flint sinks into a grieving depression over the death of Bear Ghost. Soon after replacing Bear Ghost as chief of the tribe, Ironshirt resumes his campaign of terror against the white trappers. The attacks begin in earnest in the spring, when Kamiah, who had recently given birth to a boy, Chip, is killed in an ambush by Ironshirt and his men. With Chip strapped to its back, Kamiah's horse then bolts and heads for the Blackfoot camp. Flint manages to get his son back, however, in a counterattack, during which Ironshirt is killed. Years pass, and Flint takes Chip, who is now six years old, to live in the Blackfoot camp, where, Flint believes, Kamiah would have wanted him. With the menacing Ironshirt no longer a threat, the Blackfoot gladly take Chip and Flint into their fold.