When Colgate, Ponyville's premier and only dentist, has a crisis of identity, she is swept up on a mad run through space, time, and beyond. Meanwhile, Sunset and a Trixie have borrowed the TARDIS.
Sunset Shimmer has fled back to Equestria, forced out of place by her double. The local versions of her friends try to make her feel comfortable, but Sunset is upset and scared. Worse still, she's becoming unstable again. She didn't come back alone.
The Crusaders' day trip to the city of Timbucktoo is cut short when the Doctor is kidnapped. Unseasonable storm clouds spell out a rain of terror for the tourists as they fight against a deadly foe in the sky.
Celestia, sick of her nephew's bad behavior, sends him on an adventure with the ninth Doctor. Together, they investigate a series of murders connected to a mining disaster-- or they will if they can stop arguing.
A long time ago, before Equestria was made, there was a village. There was a war. There were two sisters. There was a mad professor in a blue box. And there was the darkness that sought to swallow them all whole.
The Doctor is popping back to Earth, and he's taking his friends and family along for the ride. When the TARDIS stalls in the middle of the vortex, though, old foes arise and threaten everypony on the ship.
When a blue box containing a mysterious pony lands in Ditzy's yard, she calls for the Elements. But the more she speaks with this "Doctor," the more convinced she is that they've met already.