On May 1, 1840, a wagon train leaves Independence, Missouri for Oregon, led by old scouts Bill O'Meary and Jim Burch and the young Clint Belmet, whom they reared.

Clint warns Nancy about the arduous trip west, but she is determined and buys a sturdy rig from the half-Indian fur trapper Kenneth Murdock.

Fearing that the white man will destroy his prosperous fur trade in the Northwest, Murdock conspires with other trappers to prevent the settlers from reaching Powder River.

Meanwhile, the elderly Abby Masters, who is keeping a journal of the trip, falls in love with Jim and records the caravan's two-week fight with roving bands of Indians.

[1] In a contemporary review for The New York Times, critic Frank S. Nugent wrote: "Having so many colorful ingredients, the story must, of necessity, produce an aura of romantic adventure.