In the rough-and-tumble Nevada landscape, where every day brings a new threat to the wild mustangs’ natural way of life, can Callie save her dream horse when disaster strikes?

Plucky thirteen-year-old Callie McLean loves nothing more than to watch the herd of wild mustangs frolic near her farm in the rocky desert of Northern Nevada. School’s out for the summer, which means three months of hanging out with horses and her best friend, Billie—and three months of freedom from classmates teasing her about her hippie clothes, two-dollar words, and organic-farmer parents. Callie gets to study with their equine veterinarian all summer too.

When Callie learns her favorite wild palomino mare, Moonbeam, is in foal, she’s ecstatic. And Cloud Dancer, the golden buckskin stallion, is going to be a father. Callie can’t imagine a more beautiful pairing. But her summer idyll is broken when the Bureau of Land Management rounds up the mustangs for penning and adoption. Callie is heartbroken that the majestic horses will no longer live in the wild. Maybe she can adopt Moonbeam herself. But when the trauma of the round-up leaves Moonbeam and her new foal, Moon Shadow, in trouble, it seems Callie might lose her dream horse and the new foal forever.