Doctor Time Turner has been studying time travel for years, trying to discover a way to travel through time, and when he thinks he's done it, he calls his best friend Ditzy Doo over for tea and muffins, and shows her. But, when his machine goes haywire, and seemingly obliterates Ponyville, Turner and Ditzy have to figure out what happened, and how to fix it. The problem is, the only ponies who can help them are Princess Luna, who's slowly shifting back into Nightmare Moon, and Discord, who's slowly returning back to his evil ways.

(Takes place shortly after the 100th episode)