Cori Campbell seems like your average first grade girl. Her big sister always picks on her, and Mom is always busy either working or doing homework for her online school. Dad's job is cool enough- he works on planes with the US Air Force. They live really far away from Grandma in Okinawa, Japan, but they also live really close to the beach. Cori hears a lot about being a military child, but for her it's just her life. Cori's family is training to run a 5k race. Three whole miles! It almost seems impossible, but luckily Cori has a secret weapon. The superhero Shadow Girl. No one is stronger, smarter, or faster than Shadow Girl. With her help, Cori just might help her Dad get ready for a PT test, and cross the finish line on race day.