Traveling with his owners from Missouri to Oregon in 1848, Koda, an energetic two-year-old quarter horse, finds the long journey increasingly tedious and tiring until his young owner goes missing on the trail and he must use all his skills to find her.

"Luke Ransom was just eighteen years old when he answered an ad in a St. Louis newspaper that would change his life forever. The American Fur Company needed one hundred enterprising men to travel up the Missouri River--the longest in North America--all the way to its source. They would hunt and trap furs for one, two, or three years. Along the way, they would face unimaginable hardships: grueling weather, wild animals, hunger, exhaustion, and hostile...