In the summer of 1919 Montana, Maddie stumbles on an abandoned newborn colt, and her whole focus shifts to discovering what happened to the little horse's mama. Her search leads her through mountains and prairies, town rodeos and picnics, and into the shadow of an airplane contraption flown by none other than her missing brother Robert. Maddie is torn between learning to trust her brother or honoring the anger she's been harboring for months. With the help of her friends, her loyal dog, and a whole lot of other rodeo folk and critters, she just might solve the mystery of the missing mustangs and heal her broken family at the same time.