Andy Nelson's heart belongs in Wyoming on his family's ranch. He especially loves his thoroughbred racing horses Sapphire and her daughter, Harmony. But he understands that in order to fulfill his dream of helping animals, he must make many sacrifices on the journey to becoming a veterinarian.
Leaving the ranch isn't easy for Andy, as he first heads to the University of California-Davis and later North Dakota State University in Fargo to attain his degree. He keeps his sights on his goal and doesn't let partying or starting a relationship get in the way of his schooling. Being away from the ranch and his family is difficult, especially when tragedy arises and he must deal with the loss of his grandparents. He can, however, rely on his good friend Mikala-a fellow veterinarian student from Montana-to help him in his time of need.

Harmony follows Andy as he focuses on his goal of returning to Wyoming, tending to animals as a veterinarian, and being there for his family and his "girls," Sapphire and Harmony.