Clover Cordelia is a freshmare student at the Cambridle Academy of Magic who is determined to become a great sorceress.
Star Swirl the Bearded is a legendary wizard in need of an apprentice.
It's a tough job, working for the world's greatest wizard. On top of the usual challenges of student life there are apocalypses to deal with, and assassins who show up at inconvenient times, and plant life scheming for world conquest.
It's probably nothing Star Swirl can't take care of, provided he and Clover manage to resist killing each other first.