Emily is happy to be spending the next year with her grandfather on his horse farm. Her sister, Jen, couldn't be angrier about being stuck in the middle of nowhere while their mother is deployed in Afghanistan and their dad repairs bridges in California.
Jen is miserable at the thought of starting high school in a new town. She takes out all her frustration on Emily, who doesn't know how to help Jen see the beauty in farm life.
Emily's time on the farm gets even better when Grandpa hints that he will buy her a horse of her own. All Emily has to do is finish all the math schoolwork she's been assigned over the summer. Emily falls in love with the kind and gentle Gemini, but Grandpa declares that any horse with four white hooves is bad news.
As Emily works to get Grandpa to accept Gemini and her sister to accept their new situation, the unthinkable happens. Their mother goes missing in Afghanistan! Emily and Jen feel helpless, but their special bond holds the clue to getting their mother home safely.