It has been two years since Plenaris has been reunited. Princess Luna and Princess Celestia came to an agreement. Luna was allowed to aid Plenaris as long as it is needed for the kingdom to be independent again.
In the meantime, a map was found that showed multiple structures in the realm of Plenaris, in places rarely visited. A group of ponies was ordered to visit these places and study them, hoping to find relics or infomation to help Luna in achieving her goal and please her beloved sister.