While Starlight Glimmer is in Canterlot for a few days, a couple of ponies from Starlight's past arrive in Ponyville to entertain the locals but after seeing who lives there, they decide to cause problems instead.
Starlight did it, she passed her entrance exam and was accepted as Celestia's protege. Join her during her journey through school where she makes new friends, continues to expand her knowledge and helps other ponies with their studies.
Starlight has come of age and is now going to aid Celestia with bigger issues. What she doesn't know is that things will not only change for her, but her friends as well.
At the age of 20, Twilight Sparkle is still without her mark and since her brother is the captain of the royal guard, he could get Celestia to help her. Once Celestia realizes that she can't help her, she sends her to her protege who possibly can.
When Princess Celestia falls ill, she summons Starlight Glimmer to Canterlot to take over her duties for a few days. Celestia is confident in her protege's abilities but Luna has her doubts.
Twilight Sparkle and Starlight Glimmer are engaged in a time travel battle and no matter what she tries, Twilight just can't get Starlight to stop altering the past. The battle is growing old for Starlight so she decides to end it once and for all.
Now that the princesses are safe and Starlight as been crowned "The Warrior Princess," everypony's attention turns to Twilight, who is still under the control of Trixie. Starlight is now making plans to save her, but she won't be doing it alone.
Equestria has been split into two separate nations. Things quickly deteriorate in West Equestria and public unrest forces two princesses to abdicate, leaving one to protect the land. Can her magic stave off evil or will the nation fall?