a foreign intelligence agency organizes the kidnapping of Nyx, and DiamondTiara, who was wandering with her is also being caught, and stuck in a place at the antipodes of Equestria.

humans and their technology, ponies and their magic : who wins ?

When Twilight Sparkle wants to test an age regression spell on Diamond Tiara, Things doesn't turn out as she expected.

that's the part where Equestria is about to fall into a dystopia.