Queen Chrysalis and the changelings burst into the throne room. "HA HA HA!" she said. "At last, I have gotten my revenge on you, Princess Cadance!"
"Queen Chrysalis!" Cadance gasped.
"I have conquered your territory," Chrysalis said. "Instead of the Crystal Empire, it will be called the Chrystalis Empire! Ha ha ha!"
"Guards, seize her!" Shining Armor commanded.
The guards tried to attack, but they were still wounded from the fight with Twilight Sparkle. Their defense was pitiful, at best, and they immediately surrendered when Sunset Shimmer pulled out a hammer.
Soon, the two royals found themselves tied up in green cocoons, unable to do anything as the changelings took over.
In the Crystal Empire's dungeon, Twilight was thrown into the same cell as Pinkie Pie.
"Let me out of here! I'm the real Princess Twilight Sparkle!" Twilight shouted. "I'm not a changeling!"
"Princess Twilight?" Pinkie Pie asked. "Oh my gosh, it's been forever since we've been together!"
Twilight turned and glared at Pinkie Pie. She would have charged a magic spell to protect herself, if she hadn't used up her magic in the fight with the guards. "Stay back, Changeling!" she said. "I know you're not Pinkie Pie! She's in Ponyville!"
"No no no! You don't understand!" Pinkie said. "I'm the Human Pinkie Pie! I helped you fight Sunset Shimmer during the Fall Formal! Remember?"
"Oh yeah? Prove it," Twilight said. "Tell me something only a human would know."
"Human girls sit down to use the bathroom," Pinkie Pie said.
Twilight's eyes widened. "You're right," she said. "You must be—but that's impossible! The portal only opens once every thirty moons!"
"More like thirty days," Pinkie said. "I missed you, so I thought I'd come visit, but everything got all kooky-crazy WEIRD! All I want to do is go home now!"
Twilight hugged her lost friend. "Oh, Pinkie, I missed you, too," she said. "I miss all of my human friends, in a deep, sincere way which doesn't affect the series continuity. The fact that I only befriended you because I know your pony duplicates doesn't lessen or cheapen our friendship in any way."
"Yay, friendship!" Pinkie Pie said. "Everyone should have friends!"
"Except for the changelings, who are evil and beyond redemption," Twilight was quick to add. "We need to figure out some way to protect the Crystal Empire, before they feed on everypony's emotions!"
"Right!" Pinkie said. "But maybe we should get out of jail first." She had broken out of jail in the human world four times—long story—so she wasn't too worried about attempting a jailbreak.
Back in the human world, the Equestria Girls were being ponytastical, which is a made-up word that means "relevant to the plot of the story". A month ago, Twilight Sparkle saved their world from utter destruction, and according to my watch, it's time for them to repay the favor!
"Blah blah blah boys," Sunset Shinner said.
"Blah blah blah fashion," Rarity said.
"Blah blah blah stereotypical girl thing," Applejack said.
"Blah blah blah bacon is delicious," Rainbow Dash said.
The important conversation was interrupted, when Fluttershy ran up to the group, with a familiar purple dog in her hands. "Girls! I found Spike!"
"Aw, he's just as cute as ever!" Rarity said. She put a finger on Spike's nose. "Aren't you? Aren't you?"
Spike growled and bit Rarity, who screamed in pain. She later had to receive a painful rabies shot to ensure she didn't catch any diseases.
"Woah, what's wrong with him?" Rainbow Dash said.
"I think this is Dog Spike," Fluttershy said. "Um, that is, the Spike from our world. Not the talking Spike."
"Huh," Applejack said. She put out her hand and touched Spike's dog tags. "Says here his name is Spike Sparkle. Reckon that means he belongs to the Twilight gal who lives in the city?"
"She was here earlier today," Sunset Shimmer said. "I saw her with the human version of me."
"Wait, so that's the Twilight Sparkle everyone's been talking about?" Rainbow Dash asked. "Twilight's twin?"
Sunset nodded. "The last I saw them, they were both headed for the portal to Equestria."
"Are you sure, darling?" asked Rarity. "As I understand it, the portal is closed forever."
"The portal opens for a few days every month," Sunset said. "And it's open right now. I know, because the portal's opening is synced with my period."
A brief silence fell on the group after that.
"...Is that why you turned evil when you first came here?" Applejack asked.
"NO!" Sunset Shimmer said. "I just—pony anatomy doesn't work like—I wanted revenge on Princess Celestia, okay? Now let's just get going to the portal!"
"An adventure in Pony World? Awesome!" Rainbow Dash said.
The four female friends (and the dog) walked across campus to go to the portal. Along the way, they were accosted by Flash Sentry, who was desperately searching for his kind-of girlfriend. When they told him what happened, he frowned.
"If the portal's open again, then I'm going with you," Flash Sentry said, with a serious look on his face. "I need to see Twilight again."
Once Alicorn Twilight's magic returned, she was able to levitate the keys to the door and escape from the dungeon that way. In the hallway, Twilight and Pinkie met with the group of humans. Working together, they all formed a plan to defeat Queen Chrysalis. It was a brilliant, nuanced plan with very specific roles for everyone involved, and—nah, I'm just kidding. They decided to repeat the plan they used to get Twilight elected as Princess of the Fall Formal.
The small group of heroes threw open the doors to the throne room and ran inside. "Stop right there, Queen Chrysalis!" Twilight said. "Release my brother and Princess Cadance!"
"Yeah!" Rainbow Dash said. "Release her brother and—who?"
"Princess Cadance," Twilight said. "The pink princess."
"But you told us you were the only pony princess!" Rarity said.
"Heh heh..." Twilight chuckled weakly, embarrassed. "Guess I forgot about Cadance."
"ENOUGH!" Chrysalis said. She jumped off of the throne and stomped on the floor. Four dozen changelings burst through the windows and landed on the ground in front of her. "Changelings, kill the ponies! Kill them all!"
"Um...what about us?" Human Sunset asked. "We helped you!"
"I have no further use for you humans," Chrysalis said, predictably betraying her allies. "You can die with the others!"
"NO!" Human Twilight screamed.
"You won't kill anybody today!" Pinkie Pie said heroically. "Now that my human friends are here, we can stop you, Evil Bug Pony! It's time...to DANCE!"
Funky music started playing, as the Equestria Girls broke into a well-rehearsed dance routine. The name of this dance was The Electric Boogaloo.
Hey, hey, everybody,
We have something to say.
Hey, hey, everybody,
Hey, hey, hey.
These lyrics aren't inspired.
We think the writer's tired,
Or maybe he's not trying very hard.
So hey, hey, everybody,
We've got something for you.
Hey, hey, everybody,
Let's do the Electric Boogaloo.
At this point, the ponies danced while there was a wicked flugelhorn solo, courtesy of Flash Sentry.
Hey, hey, everybody,
We know how to sing.
Hey, hey, everybody!
Um...something something!
Dance, dance, everybody!
It doesn't matter if you're a human or a pony.
Everybody loves to dance
The Electric Boogaloo.
At this point, the two Twilight Sparkles jumped up and stood back to back. They were supposed to sing a fantastic duet piece, as part of the song's bridge. Pony Twilight started it off.
I know life can be tough,
But the power of friendship
Helps you through all of your problems!
Sadly, Human Twilight had never heard this song before, and she had no idea what the lyrics were. So she just sang the first thing that came into her head.
This has been a really weird day.
I have no idea what's going on.
I just want to go home and check my email.
"Yeah!" everyone shouted. Then it was back to dancing.
Hey, hey, everybody,
We know how to sing and dance.
Hey, hey, everybody,
Paris is the capital of France.
Hey, hey, everybody,
Don't kill and make us dead.
Hey, hey, everybody,
Let's be nice instead.
Hey, hey, everybody,
What we say is true.
Hey, hey, everybody,
It's the Electric Boogaloo!
The dance ended with everyone doing a cool pose.
Tears were streaming down Queen Chrysalis' face when the music stopped. "I surrender!" she said. "There's no way I can defeat your fantastic dance moves!"