Darby Carter loves horses, even though she's never actually ridden one. Darby's grandfather is an expert rider — in fact, he owns a horse ranch in Hawaii. So when he agrees to take her in — along with the beautiful mustang Darby saved on the range in Nevada — she knows she can't refuse, even if she is a little terrified!

But Darby's filly arrives in bad shape, and Darby's grandfather wonders if the wild horse will ever trust a human again. Can Darby take the reins and save her horse — or has she lost the mustang forever?