Tempest Shadow wasn't always the angry, relentless leader of the Storm King's fearsome hordes. Once, she was a happy filly, living with her friends in Equestria and dreaming of attending Princess Celestia's School for Gifted Unicorns. When an act of bravery costs Tempest her horn-and ultimately her magic— her life is ruined. Disappointed and bitter, Tempest flees into the world beyond Equestria, eventually setting her on a collision course with the dreaded Storm King. When he promises to restore her horn in exchange for her service, Tempest agrees to launch an epic campaign to destroy Canterlot....