Upon waking on the morning of her tenth birthday, Moxie Wyoming Woodson embarks on a summer of magic, mayhem and adventure. With rodeo champion Granny Rose as her inspiration, Moxie’s birthday dreams kick up visions of a fine young horse that will also help her take on the more grown-up chores on her family’s Wyoming ranch.

When her father unloads from his trailer the old sway-backed grey-flecked little black horse, Misty, Moxie’s hopes lie trampled in the barnyard dust. What she cannot see, but will come to discover, is that her new horse is special in more than just the way she brings this intrepid heroine into her own.

Channeling her natural instincts to care for animals and dragging along her reluctant best friend and sidekick Pickle Turner, Moxie Wyoming grows out of pouty disappointment over her broken-down mare. She transforms into a courageous sleuth, hot on the dusty and sinister trail of a menacing gang with a hard-hearted plan to round up and sell a bold and beautiful herd of wild Mustangs.

Along the way, Moxie learns there is more magic in helping endangered animals than aspiring to win rodeo ribbons.