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.

Emma's happy summer of soccer camp with best friend Luisa and visits to Rooney, the beloved old horse at the nearby stables where Annie the nanny helps out, changes when she discovers that Rooney is being sold and Luisa has some unhappy news.