Phantom Stallion: Wild Honey

The Phantom's lead mare is injured, and Samantha wants to help her. But she can't call the vet -- what if he won't let the mare return to the wild? So Sam starts treating the mare's injuries in secret. But the horse seems awfully calm for a mustang, and she matches the description of a missing mare from California. Is Sam helping a mustang, or has she accidentally stolen someone's horse?