Princess Celestia—or Tia, as her sister prefers to call her—has a fairly simple life. Stay inside as much as possible, avoid making new friends, deal with the politics of Equestria, and try to care for her easily excited little sister. But life becomes slightly more difficult when a mysterious force takes over Equestria. Reluctantly, she's forced to go on a quest to discover the mysterious Elements of Harmony with her sister. Things become more complicated, though, when a third member joins their party.