Arriving in Canterlot by train (Batman had some trouble adjusting, as he was taller than the cars had space for) the Mane Six and the Caped Crusader were greeted by a city taken over by pandemonium. The sounds of guns rattled off in the distance, and mixed with it were the screams of ponies.

A dark thought creeped into the mind of Batman. Had the Mad Doctor perfected his portal technology and set his sights on Equestria? Even if that was not the case, danger presented itself presently.

"By Celestia! What's going on?" Twilight scanned the area around her. Batman prepared his utility belt.

"I think you mean who's going on!" Announced a shrill voice. Standing atop the train station was the villain who had started this affair: the Mad Doctor!

Batman grappled atop the train station to read his lab coated foe, and help the villain by his collar. "Doctor! What are you doing here?!" Batman held the Mad Doctor atop the ledge of the building as a tactic of intimidation.

"Travelling interdimensionally, Batman. Can't you tell?"

"Batman, do you know this person?!" Yelled Twilight, blasting away nearby thugs with beams of magic.

Batman restrained the rogue with a pair of bat cuffs before throwing him onto the platform. "He's the villain I mentioned earlier. The one who threw me into the portal. If he's here then so are his henchmen. We've got to find that magic!"

Twilight eyed Celestia's castle, which was defended by elite royal guards. "There's a library even larger than mine in that castle up there. We can go there, find a spell to get you all back home, and cast it."

"Then there's no time to lose!" Spoke Rainbow Dash, readying herself for a fight.

Navigating the crowded streets of Canterlot, the ponies and Batman broke up crowds of mobsters and criminals as best they could. Rainbow Dash used her expert flying for aerial fighting, while Applejack used her strong hind legs. Pinkie Pie modified her party cannon into a non-lethal combat cannon, Rarity utilized fashionable armor, and Fluttershy used animals in the same way Batman used bats. Batman himself opted for 'ol fashioned martial arts. By the time they had reached the castle, the sounds of gunfire had died down, and royal guards were sweeping up stragglers.

Now at the court of Celestia, the ponies and Batman were greeted by none other than the castle's two royal residents: Princess Celestia and Princess Luna. Their flowing ethereal hair astounded Batman, who had never seen anything like it.

"Twilight!" Celestia greeted her star pupil.

"Princess Celestia, Princess Luna! Are you two alright?"

"Thankfully we are." Replied Princess Luna. "Who's your new friend?" She pointed her hoof at the Batman, who stood out like a sore thumb.

"My name is Batman. The criminals that attacked you came from my world through interdimensional technology. Me and Twilight Sparkle are looking for a spell to take us back home."

"We were hoping to find something in the Canterlot Library." Twilight added.

"Of course. Follow me." Celestia guided everypony to the restricted section of the library, which housed scrolls and books on subjects too confidential and powerful for the average pony. "Starswirl the Bearded wrote a thesis on interdimensional travel after he graduated from the Royal School of Magic." She pulled a thick scroll from one of the shelves. "In it are spells which should help you and your friends."

Twilight unrolled the scroll, layers of dust floating from the aged parchment into the air, and studied its contents. "This is exactly what we need, Princess! But we're going to need to cast it across the entire city. Think you and Luna can help?"

"Of course." They said in unison. The alicorns put their horns together, and sent a magical shockwave throughout Canterlot. The Mad Doctor and his goons began to fade away from this reality, their bodies being sent to where they truly belong. Batman also found himself fading away,

"Twilight Sparkle, before I'm sent back to my world, I'd like to thank you for your help. I don't often employ allies, but I was a fish out of water here. Maybe I can apply this friendship lesson in my city."

"It's been a pleasure, Batman." Twilight replied.

With that, the Dark Knight found himself back in Gotham City. As did the Mad Doctor, who was still restrained in bat cuffs. Batman sent an "anonymous tip" to G.C.P.D. and soon the lab was swarming with cops, but by then the Batman had already left.

On the other end, Twilight Sparkle and her friends found themselves having saved the day once again.

"So, I'm just gonna say it." Rarity started. "That giant bat symbol was his cutie mark, right?"

"Oh yeah."

"No doubt."

"For sure."