The Lawler family is moving west, heading for Oregon along the Oregon Trail. Their wagon train got a late start, and because of that, they reach Ft. Laramie, Wyoming, much later than they should. When the train members come to understand their tardiness, they set out cross-country to pick up the Bozeman Trail, with the notion of heading to Bozeman, Montana. The Lawlers' wagon is disabled, and Caleb Lawler comes down with what the other party members believe is cholera. The Lawlers are, left by the other emigrants, who promise to send help. The Lawler children, Andy, Anne, Maggie, and Jerusha, are alone, after their parents die. They set out to follow the others across the Wyoming plains. When they find the wagon train has been, attacked by Indians, they change direction, deciding to cross the mountains to get to their destination more rapidly. It is a very wrong decision, but they have no way of knowing that.
