I-Cam

Tate has always been a little too adventurous, she lives on a small farm in Jasper, Nevada, one day while riding her horse she stumbled upon Smokescreen: an alien from space. Another day on a horse trail, Tate is soon found by Starscream, her sister and best friend, Cam, decides to become Starscream's servant in exchange for her sister's life.
Cam hates how boring her life is. The best part of her life is street racing, and horseback riding. One day when on a horse trail she decides to protect her sister, whom her mother has always loved more than her, and becomes Starscream's servant.