Mikayla and Maximilian Summer get thrown into Equestria. That's not all though. Mikayla is stuck as Nightmare Moon, while Max is stuck as a Pegasus filly named Nightingale. The two end up outside of Ponyville, vastly confused. Who wouldn't be confused when they get turned into a pony! And in Max's case, a pony of the other gender.
Chaos ensues.