Sunset Shimmer was flung backwards through the air and landed hard on a metal floor. Dazed, she looked up just in time for Rarity to land on top of her with a thump. Glancing up through a mess of purple hair, she saw a great cloud of dark energy floating above some sort of generator that was smoking profusely.

As Sunset watched, Fluttershy and Applejack came hurtling through the cloud and landed in a heap on top of Rainbow Dash and Pinkie Pie, who were already in a tangled mess themselves. Once they were through, the dark mass started writhing madly until, with a rumble that shook the room, it disappeared, leaving only ruined machinery behind.

"What in the heck was that?" Applejack asked, wincing as she tried to climb off Pinkie.

"I have… no idea," Sunset huffed. All she could see, apart from the smoking machine, was that they seemed to be in a dark room with dirty metal walls. "Is everyone okay?"

Rarity mumbled something inaudible, then lifted her face from Sunset’s chest. "I think so?"

"I will be when Flutters shifts her elbow from my ribs," Rainbow moaned.

"Oh! I-I’m so sorry!" Fluttershy spluttered.

"Uh… girls?" Twilight called tremulously.

Rarity clambered off Sunset and helped her to her feet. Looking around, Sunset saw what had Twilight’s attention.

Four men were standing in front of the girls, all with looks of utter shock on their faces. Two of the men were wearing simple blue jumpsuits, one with brown skin and the other with skin almost as pale as Rarity’s. The third was wearing a lab coat and had light peach skin tones; probably a scientist. All three had iron-grey hair. The last, with black hair, darker peach skin and wearing some sort of riot gear, was standing protectively in front of the others. He was clutching a metal baton and looked like he wasn’t sure whether to attack or not.

"Er… hi?" Sunset ventured.

The brown-skinned man was the first to recover. "What in the world? What the hell is going on here!?"

The pale-skinned man in the jumpsuit moaned fearfully, taking several steps back. "They must be some kind of mutants from outside! I mean, Jesus, look at their skin! And their hair!"

"Mutants?" Twilight asked quizzically.

Sunset glanced around at the others, puzzled. There didn’t seem to be anything wrong with them aside from a bit of dirt and some scrapes.

"And what exactly is wrong with our hair and skin?" Rarity asked testily.

"Easy now, Rarity," Applejack said quietly.

Sunset was worried. Seven girls randomly appearing out of nowhere had understandably unnerved the men, and things could easily turn ugly if something wasn’t done to defuse the situation. She slowly raised her hands, trying to show she wasn’t a threat. "I think there’s been some sort of misunderstanding. We didn’t mean to come here, we were involved in an accident and-"

Sunset made to step forward, then flinched and stopped in her tracks as the man in the riot gear pointed his baton at her. "Don’t you come any closer! I’m warning you!"

Sunset obligingly stepped back. "Please. We don’t mean any harm."

The brown-skinned man in the jumpsuit snorted loudly. "No harm indeed! Where the hell did you… things come from?"

"I think we all need to calm down here before anyone gets hurt," The scientist said suddenly. He turned to the brown-skinned man. "These people don’t look dangerous, Overseer. Surely we can give them a chance to explain themselves?"

There was silence as the Overseer folded his arms, glaring at the girls. "Very well, James. You... girls... have one chance to explain yourselves. But be warned, if you do anything that seems even remotely like a threat I’ll have Officer Gomez put you all down in an instant."

"I’d love to see you t-mmphh!" Rainbow’s challenge was cut off as Applejack clamped a hand over her mouth.

Sunset considered their options. She was confident that her friends could handle these men with their magic easily enough, but she hoped it wouldn’t come to that. She had a sneaking suspicion that the vortex had dumped them in another world and wasn’t entirely sure their magic would work here, or if magic even existed here at all.

Taking a deep breath to calm herself, Sunset decided it would be best to just tell the truth, or, at least, some of it. "My name is Sunset Shimmer. Me and my friends were working on some experimental equipment when something went wrong."

The men listened carefully. The scientist, James, seemed particularly intent on every word Sunset said.

"I don’t know exactly what caused it, but a mass of energy like the one you just saw sucked us in and somehow transported us here," Sunset continued.

"Never seen a backup generator do anything like that before," the pale-skinned man cowering at the back muttered.

"Quiet, Stanley!" the Overseer snapped, before turning back to the girls. "You expect me to believe that you seven were working on some sort of highly advanced technology that just happened to go wrong and randomly teleport you straight into our Vault?"

"It’s the truth," Twilight said earnestly. "We picked up some strange electrical readings coming from somewhere we couldn’t figure out, but we didn’t have a chance to shut down the machinery before everything went wrong."

The Overseer looked over his shoulder at the cowering man. "Stanley! When was the last time you checked this backup generator?"

Stanley flinched as if he had been struck. "Day before yesterday, sir. I make sure to check it twice a week as per regulations."

"Did you find anything suspicious?" The Overseer asked.

"Looked the same as always," Stanley replied with a shake of his head. "A Radroach had chewed through one of the wires, but I cleaned it up and replaced the wire just like it said in my report."

The Overseer turned back to glare at Sunset. "Where exactly have you girls come from?"

"Canterlot High," she replied quickly.

The Overseer raised an eyebrow. "Canterlot High?"

"That’s the school we were at when all of this happened," Twilight supplied.

"A school?!" the Overseer spat incredulously. "You honestly expect me to believe that there is some decrepit school out there in the Wasteland with access to that kind of technology?!"

"I’ve heard of it," James cut in quickly. "I think it’s a part of the Institute, up north in the Commonwealth." He winked at the girls and put a finger to his lips, then whipped it away a heartbeat later as the Overseer turned to him.

"You’ve never mentioned this before," he said suspiciously, narrowing his eyes.

"You did ask me to avoid speaking of my time outside at all costs," James replied evenly. "There were rumors circulating that Canterlot High were a rogue element experimenting with dangerous teleportation technology. I never believed it might actually be real, though."

Looking more perturbed than ever, the Overseer turned to the girls again. "Is this true?"

"Er…" Sunset hesitated. James subtly nodded his head. She had no idea what he was talking about, but he seemed to be trying to help. "Yes, sir, it is. We thought the safety features we had implemented were adequate but... apparently we were wrong."

"Clearly," the Overseer sneered.

Sunset lowered her hands. "Please, we don’t want to cause any more trouble. We just want to find a way home."

"And what’s to say there aren’t going to be more of you turning up out of thin air and causing even more havoc?" the Overseer asked.

Sunset indicated the still-smoking machinery behind her. "Frankly, the last I saw, the equipment on our end was in even worse shape than this."

The Overseer mulled this over for a bit. "Alright, let’s say I believe you about this being an accident." He gestured vaguely at the girls. "It still doesn’t explain your grotesque mutations."

Rarity squawked indignantly. "Grotesque!?"

"Easy, Rarity," Applejack said again, though she was frowning at the Overseer herself.

Twilight looked around at the others in confusion. "What do you mean by mutations?"

Looking at the four men in front of her, it slowly dawned on Sunset what was wrong. It was just a hunch but, aside from the dark-skinned Overseer speaking at the front, the other three had varying shades of peachy-colored skin, whereas the skin tones of Sunset and her friends were all wildly different colors.

"Perhaps it’s a side effect of whatever energy is given off by the teleportation experiments?" James suggested quickly.

"Radiation levels?" the Overseer asked instantly, nervously checking a device on his forearm.

"Nothing I can detect from here," James replied, frowning at a similar device on his own forearm. He stepped up to Sunset, ignoring a hissed warning from the man in riot gear. "May I?" he asked, holding out his arm.

Sunset simply nodded, staying perfectly still as James passed the device on his forearm over her body. Frowning, he turned to the Overseer. "It seems they aren’t giving off any radiation whatsoever."

Stanley let loose a sigh. "Well that’s one less thing to worry about, I suppose."

"Might I suggest we keep them quarantined for the time being," James said as the Overseer glared at Stanley. "Let me run some tests to check for infections. If they are clean, then we can decide what to do with them from there."

Sunset didn’t like the thought of that, but then she supposed it was a sensible plan under the circumstances.

The Overseer didn’t seem to like it either, but at last he relented. "Very well. stand down, Officer Gomez." Officer Gomez relaxed slightly. Sunset was glad to see him lower his baton, but she’d feel a lot more comfortable if he put it away entirely.

"I want these girls kept contained here on this level. Put them in storage room D for now," the Overseer ordered.

"Storage room C might be better sir," Stanley put in. "It’s got a toilet," he added quickly as the Overseer rounded on him.

"Fine," the Overseer huffed. "Stanley, you will lock these girls in room C, and then I want you to stay down on this level until James has given these girls a complete inspection."

James nodded in approval. "I’ll have Jonas handle the clinic while I run the tests I need. He can manage for a few days."

"Good. I also want you to check for any genetic aberrations while you are at it," the Overseer instructed him. "Officer Gomez, I want you to make sure these girls do not leave the storage room until I say so. If they attempt to leave you are to treat them as hostile and deal with them accordingly."

"Yes, Sir," Gomez replied.

"I shall have Andy sent down to cover you for breaks, but I want you to stay on this level as well until we are sure that all is safe." The Overseer looked back to the girls. "I want you all to follow along quickly and quietly. Should you try to run, or do anything foolish, you will be dealt with immediately, and severely."

Sunset nodded stiffly at him, biting the inside of her cheek to stop herself from saying something defiant.

The Overseer nodded to Stanley. "Now then. Stanley, lead the way."

The girls followed Stanley as he led them out of the room. Officer Gomez, James and the Overseer brought up the rear, making sure the girls didn’t dawdle or try to run. Sunset shivered as they were marched through a series of dark and dismal rooms.

None of the girls dared to speak until Stanley stopped outside a heavy metal door. Twisting the handle, he hauled it open and stood aside, gesturing for the girls to enter. There were a few large metal crates stacked against the one wall and several smaller boxes scattered around haphazardly. A toilet could be seen through an open door in the corner.

Sunset turned as James and the Overseer entered the room after them. "How long will we be in here for?"

"Until I decide that it is safe to do otherwise with you," the Overseer responded imperiously.

James stepped forward, pulling a little notepad and pencil out of his pocket. "I’d like to take down your names, if that‘s alright?" He nodded to Sunset. "You said your name was… Sunset Shimmer, correct?"

"Yes, and this is Twilight Sparkle, Rainbow Dash, Applejack, Fluttershy, Rarity and Pinkie Pie," Sunset replied, indicating each of the girls in turn.

"Interesting names," James muttered, smiling faintly.

The Overseer snorted and stepped over to the door. "You are to stay here in this room until I decide otherwise. James will be down periodically to perform whatever tests he deems necessary." He looked them all over one last time. "So long as you behave yourselves, I shall have someone sent down with food for you at appropriate times."

"Are any of you girls allergic to anything?" James asked.

The girls all shook their heads. The men both left the room and closed the door behind them. There was a loud clang as it was locked. Sunset slumped down on a box, rubbing her sore arms as the others all collapsed on boxes or the floor around her. "Well that could have gone better," she muttered.

"Agreed," Rarity snorted. "Grotesque indeed!"

"Can someone please explain to me what just happened?" Applejack asked, massaging her temples.

"Something must have gone wrong with the machine, it’s the only thing I can think of," Sunset replied.

Twilight wiped a smudge off her glasses. "Yes, but what? The Diviner wasn’t picking up any magical signals whatsoever apart from our own." She hung her head sadly. "I’m sorry, girls, this is all my fault."

"It’s not your fault, Sugarcube," Applejack said gently as Pinkie threw an arm around her.

"Of course it’s not. There was nothing any of us could do." Sunset frowned, thinking hard. "It must be something to do with those electrical signals we picked up. Whatever they were they must have affected this place too, or we never would have been pulled here."

Rainbow kicked at a box. "Speaking of here, just where the heck are we? And who were those jerks?" she growled.

"And why did they think we were mutants?" Twilight asked.

Sunset held out her arms. "It’s just a hunch, but apart from the Overseer the others all had similar skin colours. Maybe being different and brightly coloured isn’t exactly normal in this world?"

"This world?" Rarity asked, raising an eyebrow. "You think we’ve been brought to another world like Equestria?"

Sunset shrugged. "Not like Equestria, but that portal certainly dumped us somewhere."

Twilight nodded. "That would make sense. The mirror was connected to the portal to Equestria. The interference we picked up could have been signals coming from this world."

Sunset thought back to what had happened with the Diviner. "So when Princess Twilight switched off the machine on her end we lost the connection to Equestria, but the mirror picked up the connection to this world instead?"

"That seems likely," Twilight agreed. "James did say that there was a group here that was studying teleportation technology. We might have accidentally gotten caught up in one of their experiments."

"That’s if he was telling the truth about those experiments, I get the feeling he was making that up," Sunset told her.

Rarity frowned, picking dirt out of her hair. "He did seem to be covering for us for some reason."

"Maybe he just doesn’t like that big mean Overseer," Pinkie mumbled.

"James was much nicer than the others," Fluttershy added quietly.

They girls fell silent for a moment. Sunset was desperately trying to think of a way out of their situation, but nothing came to mind. Breaking out of captivity with their magic was probably possible, but she figured that it wasn’t worth the risk. Their captors were only trying to protect themselves, and hadn’t actually hurt any of the girls yet. For the moment, it seemed the best idea was to wait and hope that they were allowed out soon.

While she was busy thinking, Applejack suddenly spoke up, "What do you suppose happened to Principal Celestia and Vice-Principal Luna?"

Twilight leaned back with a sigh. "They didn’t come through the portal with us, so they’re probably trying to figure out what happened."

"But what can they do?" Fluttershy asked.

Sunset slumped, dejected. "Not much from their end, but hopefully Princess Twilight will work with them on a solution."

"What if the portal to Equestria was damaged?" Rarity asked anxiously.

"Not likely," Twilight said, shaking her head. "It looked like Princess Twilight managed to switch their portal off before anything too bad happened. Hopefully she can come through the portal to Canterlot High and help repair the Diviner."

Sunset stood, placing her hands on her hips. "Either way, we’d best behave ourselves here, at least until these people let us out and we can start looking for a way home ourselves."

Applejack looked up, rubbing her neck nervously. "Do you think Principal Celestia will have told our families by now?"

The others looked at each other anxiously. Sunset realized she had it easier than the other girls. Most of the people who cared about her were stuck in that storage room with her.

"They’ll be so worried about us." Fluttershy noted, her voice wavering.

"It‘s okay!" Pinkie shouted, jumping to her feet. "They may be worried, but I know they’ll never stop looking for a way to bring us back!"

Sunset grinned. "Pinkie’s right. They won’t give up, and neither should we."

Rarity stood as well, striking a defiant pose. "Indeed. After all, we've been through worse and come out stronger than ever!"

Twilight climbed to her feet too. "That’s right! As long as we’re together we can get through anything!"

The girls started to chatter excitedly, then fell quiet as they heard voices outside the door. There was a loud clang as the door was unlocked, and they watched nervously as it was hauled open. Officer Gomez stepped through the door. Sunset was relieved to see that he had at least put his baton away.

James followed Gomez into the room, looking around at the girls. "Are you all alright?"

Sunset ran a hand through her hair. "We’re okay, just a little overwhelmed by what’s happened."

James smiled slightly. "Understandable. You gave us all quite a fright too, to be honest."

Sunset sank back onto the box. "We’re sorry. We didn’t mean for any of this to happen."

"Well, you haven’t caused any real harm yet," Officer Gomez said bracingly, "I’m sorry I was a bit aggressive with you earlier. As long as you girls behave, I’m sure we’ll have you out of here just as soon as the doc gives the all clear."

"And I’d like to get started on that right away." James held up a small medical kit. "Would you mind waiting outside while I examine them, Herman?

"Alright, doc, if you insist. Just shout if you need anything." Gomez left the room, closing the door gently behind him.

James set down his medical kit and checked the door before turning back to the girls. "I’m sorry about this, I fear it may be my fault that you’ve been brought here," he said with a somber look.

The girls exchanged glances before looking back at James. "What do you mean?" Twilight asked.

James sighed heavily. "I’ve been doing experiments in secret down here with my assistant. One of the experiments I was working on involved a device I discovered before I gained entry to the Vault. I haven’t really had a chance to test it until recently."

"What sort of device?" Sunset asked.

"Honestly? I’m not sure," James replied. "I’ve never seen anything like it before. I’ve been setting it up, testing it and putting it away without anyone noticing for a little while now, hoping I could use it to help with my research."

"What does it do?" Twilight asked curiously.

"I thought at first it was some sort of energy converter, but when I switched it on today it started pouring out that dark cloud that you girls came out of." James shook his head in confusion. "Tell me, what kind of technology were you working on?"

Sunset paused, not sure what to tell him. Seeing her hesitation, Twilight spoke up, "It was a machine designed to detect magic."

"Magic?" James asked, looking even more confused. "What do you mean, magic?"

Twilight touched the Geode around her neck and extended her arm. A purple glow surrounded one of the boxes as she used her magic to lift it several feet into the air.

James stepped back, gazing at Twilight in shock. He quickly recovered himself, smiling and shaking his head again. "I see. Some sort of technology that manipulates magnetic fields, I assume? Very impressive. I hardly see any reason to call it magic, though."

"Oh really?" Sunset asked coyly, grinning at the other girls.

Applejack chuckled as she hefted one of the heavy crates and held it above her head one-handed, scraping it against the ceiling. James’ mouth dropped in amazement. Rarity held out her hands and a complex arrangement of gemstones materialized above them. There was a rainbow-colored blur as Rainbow Dash darted all the way around the room several times, finally stopping and leaning against the wall with a smug look on her face.

James stood slack-jawed in amazement. "Incredible," he breathed. "Simply astonishing," He looked in disbelief at Twilight. "I never believed magic existed."

"Perhaps it doesn’t in this world," Fluttershy put in quietly. "It didn’t in our world at first, either."

"Your world?" James raised an eyebrow at her.

"Yep. Our world used to be ordinary ‘til a connection got opened up to Equestria," Applejack replied.

"Equestria?" James was looking more and more baffled by the second.

"It’s the world I’m originally from, it‘s where all of our magic comes from," Sunset answered.

Twilight nodded. "Recently, we’ve been having trouble in our world with magical artefacts and creatures that came to our world from Equestria. That’s why we built a machine that could detect magical anomalies before they become a problem."

"It also allowed us to communicate with our friends in Equestria, which is what we were doing when everything went wrong and we were sucked through to here," Sunset said sadly.

James scratched his beard, looking thoughtful. "You say you were communicating with another world, Equestria, when you were brought here. Do you think that is what the tool I found was? Some sort of… magical transportation device?"

"I don’t think so, we didn’t detect any magical signatures other than our own." Twilight replied, frowning. "Perhaps it’s some kind of dimensional technology that interfered with our portal when you switched it on?"

"Could we take a look at it?" Sunset asked.

James shook his head, his face grim. "I’m afraid not. It was completely destroyed when that dark cloud consumed it."

Sunset’s heart fell at that. Without it, she had no idea how they were going to get back home.

"I‘m glad you were quick on the uptake earlier, when I lied about the Commonwealth," James said. "I was trying to protect you and buy some extra time. The Overseer will go to extreme lengths to protect the safety of the Vault."

"Does this Commonwealth really exist?" Twilight asked hopefully

James nodded. "I think so, I’ve heard rumors about them over the years. Nothing about teleportation, though. They were simply the only group I could think of that the Overseer won’t know much about, so he wouldn’t be too suspicious."

"Do you think they could help us?" Pinkie asked.

"I doubt it, to be honest. Even if they could, getting there across the Wastes would be an almost impossible journey, even for girls with abilities such as yours. Incidentally I wouldn't let the Overseer or anyone else know about your powers, we don’t know how they may react." James started digging around in his kit. "First of all, let's get these tests done. If everything comes back clean, I’ll see if I can convince the Overseer to let you stay in the Vault. At least until we can find you a way back home."

"Thanks, James," Sunset said gratefully. "What tests do you need to do?"

"For the moment, just a cursory examination for any rashes or lesions. Nothing too severe or intrusive," James replied. "Plus a few blood samples from each of you, if that is alright?"

Sunset nodded with a sigh. "Whatever you need." The other girls all agreed too, allowing James to quickly examine and take a sample from each of them. He worked quickly and efficiently, treating them all gently and quietly reassuring Fluttershy when she was intimidated by the needle. He was clearly a skilled doctor, and a kind man.

When James was finished he quickly turned to leave the room, but as he opened the door he turned back to the girls, smirking. "This is something I never thought I would find myself saying to anyone," he muttered, half to himself.

"What is it?" Sunset asked, expecting a comment about magic.

James smiled grimly. "Welcome to Vault 101."

Just a quick note, I described the skin colors of the various men in this chapter without referring to race as from an equestria girl (or pony) pov skin color is an individual thing not a race thing. Probably pointless to even mention that, just don't want to come across as unintentionally racist.