We pick off at the end of Season 6, episode 22: where the treature chest Rarity opens turns out to be cursed.

As the curse spreads through Equestria, Twilight and her friends are forced to find a way to get rid of the curse, and find a way to defeat the villain - and keep Equestria calm and safe - all at once.

Based of a point raised in LittleShyFiM's Cinemare Sins video on this episode.

UPDATE 12.06.23
This story has been officially cancelled.