As the Friendship Express left the outskirts of Ponyville and began making its way across the plains towards Canterlot, Sonic, Spike, and the ponies were settled in for what they expected to be a long ride, still listening to the music coming from Sonic's cell phone. They were all lightly bobbing their heads in time with the music, a few like Spike, Twilight, Applejack, and Shining Armor even moving in their seats like they were dancing.

Soon, the upbeat song that was playing came to an end and everybody settled down in their seats again. "Mm, those are some good tunes ya got there, Sugar-hog," Applejack commented.

"Yeah, you got anything else that sounds awesome?" Rainbow Dash asked.

Sonic shrugged, "Yeah, I've got plenty of other tracks on here. Hang on; let me find something else…" He held his phone in both hands and began sliding his left thumb over the screen, flipping through his music library.

At the front of the train, meanwhile, Tails and Pinkie were working to keep the Friendship Express going. For the most part, Pinkie was getting into the role of conductor and was piloting the train while Tails was checking everything to make sure they were well prepared. "How does the water supply look, Pinkie?" the fox asked while checking some of the gauges from behind the pink pony.

"Super duper!" Pinkie replied as she sat and looked straight ahead at the boiler.

"Okay, good," Tails murmured. He looked back over his shoulder at the coal littering the cabin and said, "We should have plenty of coal here to get us to Canterlot. I guess we're good to go, then." He walked over to the window on the right side of the cabin and pressed his right hand against the frame as he stuck his head out, looking up at Canterlot in the distance as the wind from the train's movement blew in his face. It looked like they had a long way to go, but at the speed they were going, they should arrive in no time.

Looking back down, Tails' eyes went wide as he gasped, "Whoa, what the - ?!" He pulled his head back inside the cabin sharply and exclaimed, "Pinkie, hit the brakes!" The startled pink earth pony leapt up at his shout and did as he said, pulling the lever for the brakes.

Back in the second coach from the engine, the rest of the group was thrown for a loop when the brakes started slowing down the train, Sonic, Spike, Applejack, Fluttershy, and Rainbow Dash being jerked forward while Twilight, Rarity, Shining Armor, and Cadance were yanked backwards, all of them letting out a gasp of surprise at the sudden stop. Rainbow Dash was sent tumbling from her spot atop the seat Sonic and Spike were sitting in and she probably would've landed on top of Spike had Sonic not managed to get his hand in front of the baby dragon in time to keep him from being sent flying out of his seat.

Everybody sat back into a normal sitting position a few seconds after the train slid to a halt, save for Rainbow Dash who was lying on the floor at Twilight and Rarity's hooves. "Ow… what the hay?!" the rainbow-maned pegasus groaned as she lifted her head up and rubbed the back of it with a hoof.

"Oh… I really did not like that…" Fluttershy murmured.

Applejack patted her on the back with a hoof, "Don't worry, Fluttershy. Whatever happened to cause that, we're fine."

Cadance looked out the nearby window and noticed what little scenery there was wasn't moving anymore. "We've stopped! But why?" she wondered.

She was about to receive her answer, as seconds later, the door leading to the front slid open, everyone looking to see Tails and Pinkie standing on the other side of it. Sonic, who was helping Rainbow Dash up onto her hooves, looked up at Tails and asked, "Tails, what happened, man?"

Tails scratched the back of his head as he replied, "Uh, sorry about the sudden stop, guys, but we've got a bit of a problem."

Pinkie piped up before he could continue, "There's a big, whirly portal up ahead, like a big tunnel! We would've gone through at the speed we were going!"

Sonic turned towards his window, walked over to it, and slid it up, poking his head out and looking towards the front of the train. "Shoot! You guys were right to stop the train! That thing's right in the middle of the tracks!" he said.

Shining Armor, who was looking out the window on his side, added, "And you weren't kidding when you said 'big', Pinkie Pie! The only way we'll be able to get the train around that is if we pick it up off the tracks!"

As the two pulled their heads back inside, Twilight asked, "Do you have any idea where it leads, Tails?"

The fox answered, "No. That's why I told Pinkie to stop the train. If there aren't any tracks on the other side, the train could get really messed up, and that would cut our trip short."

Rarity asked, "What are we going to do now? The Princesses didn't use their magic, so they're still on their way to Canterlot! We can't ask them to send a carriage right now!"

Rainbow spoke, "What's the problem, Rarity? Shining said we could go around the portal if we lifted the train off the tracks. We'll just have Twilight do it and we'll be on our way!"

Tails spoke, "I don't think that'll be necessary, Rainbow. I checked my radar while I was up front. If the readings I got are correct, then that portal isn't entirely stable. If we go in there, we might be able to find a way to close it, or at least open up a new portal behind it that we can use so we don't have to abandon the train."

Pinkie clapped her hooves on the fox's shoulders from behind, saying, "Now you're thinking with portals, Tails!" She pushed herself off of him and, while she was still on her hind legs, tossed off her pilot's hat and neckerchief. She then said, "Come on, gang, let's see what kind of mystery is on the other side!"

Rainbow piped up, "Hey, I'm all for having another awesome adventure, but why can't we just go around it? We could just lift the train off the tracks like Shining said, or we could just use the Warp Ring to get around the portal!"

Twilight spoke, "I know we have to get to Canterlot, Rainbow Dash, but we've investigated all the other portals we've seen so far. We're not exactly in Ponyville anymore, but as long as it's right here, we should still see where it leads."

Shining nodded, "I agree, Twily, especially since Tails said it was unstable. What if something happens because we didn't investigate?" Twilight glanced to the side at him at that.

Spike looked up at Sonic and asked, "Do you think we've got enough time to go check it out, Sonic?"

The blue hedgehog looked down at him and replied, "We'll make it quick. If it's unstable, we shouldn't be in there long." He then looked at Tails and asked, "You're sure it's stable enough to go in there, right Tails?"

Tails nodded, "Yeah, I think so. My radar started acting weird while it was getting the readings. That's what makes me think it's unstable, but I'm not entirely sure. We should be fine, though."

Cadance stood up, "Then let's go. We don't want to keep Aunt Celestia and Aunt Luna waiting any longer than we have to." Everyone else agreed with her and they all stood up, all of them making their way to the nearby exit and climbing down off the train.

Quickly making their way to the front and going past the engine, the group soon stood in front of the portal blocking their way. The image on the surface seemed to be showing an underground cavern, but every few seconds, the image would become distorted before returning to normal. When that happened, it almost looked like static on a television screen. This only slightly confused everyone, though, since Tails had already said there was something strange about the portal. With this in mind, they all leapt into the portal, ready to see where it would take them…


Everyone landed feet/hooves first on solid ground and quickly scanned their surroundings. Just like the image on the portal had suggested, it appeared that they had touched down in some sort of underground cavern. They could see water coming down in falls in places off in the distance and what appeared to be some green lights brightening and dimming nearby. Looking back, they could see the portal they had just come through on one of the cavern walls.

"What is this place?" Rainbow wondered out loud.

"I have no clue. I've definitely never been here before," Sonic commented.

Spike looked up at him, "Really? You haven't?"

Sonic replied, "Hey, I've seen quite a few underground places before, but this is totally unique. I'm pretty sure I'd remember this." He glanced over at Tails and, upon seeing the fox looking down at his radar, asked, "Hey, Tails, are you getting anything?"

Tails answered, "No, not really. All I'm getting are those weird readings I picked up before." Sonic, the ponies, and Spike (who climbed up on Twilight's back) looked over his shoulders at the dual screens and saw what he was talking about. The radar seemed to be functioning normally, but the numbers and other readings on the bottom screen kept jumping every few seconds.

"Is it still okay fer us ta be here, darlin'?" Applejack asked.

Tails looked up at her, "Yeah, it should be."

Shining spoke, "Let's get moving, then. The sooner we're done here, the sooner we can get back to the train." With that, everyone started moving deeper into the cavern, no one noticing the portal behind them beginning to waver at the edges. After they rounded a corner, it sparked with electricity for several moments before it started to shrink, completely closing and vanishing after a few seconds…

As the group made their way through the cavern, they were quick to notice that the ground was uneven in a number of places, forcing everyone to climb on top of the parts that stuck up since the ground wasn't sloped in a lot of places. Strangely, it almost seemed as though someone had cut or chiseled the rock to give it the appearance they were seeing. This was further compounded when they saw, at the places where the ground did slope, there were green ramps to make straight slopes that were clearly not natural. Who had been down here, and for what purpose?

Walking between two small waterfalls, Sonic eyed one of the sources of the green lights they had seen earlier, noticing it was circular-shaped and seemed to be embedded in a rock column. "Some kind of crystal, maybe?" he wondered to himself.

Twilight looked at it as she and the others followed him between the waterfalls. "Strange…" she murmured. She faced forward after a moment and noticed Sonic had stopped just ahead. Looking past him, she saw the reason. "Is that a bridge?" she asked as she stopped next to Sonic.

The others stopped as well, all of them looking at it. "It is a bridge, Twilight. Strange how it's green like so many other things down here, though," Shining said.

"That's fer sure. Even some o' these rocks look green from a distance," Applejack commented.

Rainbow spoke, "Who cares what some rocks look like? Let's see where this leads!"

Spike drooled a bit, "Oh man… It looks like a bunch of emeralds all strung together…"

Rarity spoke, "Spike, please! Act like a proper gentleman!" Spike snapped back to attention at her words and stood up straight, quickly wiping the drool off of his mouth. Rarity then spoke again, "That's better. I understand your excitement, darling, but this bridge is to be walked upon and nothing else. I am assuming it is strong enough to be walked on; after all, why else would it be here?"

Tails looked at the bridge carefully. "It kind of looks like those ice bridges we crossed when we were at those ice mountains. It should be just as sturdy," he said after a moment.

Sonic lifted his right foot, "Let's see." He set it down on the first segment, which immediately lit up as soon as his foot made contact. Everyone tensed up for a moment, but Sonic soon relaxed and started walking across the bridge, each segment lighting up as he walked. He reached the other side and called back, "No problem! Come on!" Everyone began making their way over the bridge to him at his reassurance.

As she walked across the bridge, Twilight looked off to the side, looking at the waterfalls and glowing lights. "This place reminds me of the caverns below Canterlot," she mused to herself, glancing over at Cadance for a moment. Her favorite foalsitter did not appear to be worried, but Twilight wondered if she was thinking of the crystal caverns as well.

Tails was the last one across, the fox looking down at his radar as he walked behind the others. "Weird… We've gotten pretty far away from where we entered from, but nothing's changed! The readings are still weird and I'm not getting a good signal," he thought.

He was brought out of his thoughts when Pinkie yelled, "Look out!" He looked up, only to see the party pony leaping towards him, practically tackling him onto his back as a silver-looking bat swooped down where his head had been. Not even a second after he landed on his back, Rainbow Dash shot up and delivered a flying kick to the bat, sending it crashing into a wall. It broke as soon as it hit the wall, revealing that it was actually a Badnik.

Pinkie grinned down at Tails, "You've gotta pay more attention, Tails! Good thing my Pinkie Sense told me you were going to get attacked from above!"

Tails cheeks turned a bit red under his fur, "I… see. Well, thank you, Pinkie!"

Sonic came over and helped Tails to his feet after Pinkie climbed off of him, asking, "You okay, Tails?"

The two-tailed fox nodded, "Yeah. That was my fault. I should've been looking around rather than down at my radar."

Rainbow Dash hovered overhead and said, "Heh, don't worry, Tails. I know how you eggheads just LOVE to get absorbed in whatever you think is so fascinating!"

Pinkie piped up, "Ooh, ooh!" When Sonic, Rainbow, and Tails looked at her, she reached into her mane and pulled out Tails' radar. She held it out to him as she said, "I grabbed this so it wouldn't get smashed! Here you go, Tails!"

Tails smiled as he took it from her, "Heh, thanks, Pinkie!"

The four of them heard Applejack call, "Hey! Y'all okay back there?" They looked to see everyone standing up ahead, starting to come back towards them.

Rainbow called back, "Yeah, we're cool, AJ!" The four of them then hurried to rejoin the rest of the group, passing by one of the green lights as they went. A second after they passed it, its surface changed from green to a grayish snow color…

A short while later, after dealing with more bat Badniks and some red dinosaur-like Badniks, the group came across what appeared to be a green tube going down into the rocky ground. The ground around it appeared to be made of emeralds, and there were little bits of emeralds littering the ground around it. While Spike and Rarity gathered the emerald bits up, the others gathered around the tube, looking down at it.

"Now what do y'all suppose this is here for?" Applejack asked.

Twilight put her face close to the ground and peered down into the tube. She spoke after a moment, "Is that… I think that's water down there."

Sonic quickly said, "Then we're not going down there. Last thing we need is to run into a dead end underwater, or for that tube to not empty out."

Fluttershy shivered, "Ooh… that sounds like it would be scary."

Shining nodded, "It does, Fluttershy, but I still wonder what this pipe is for. It must be here for some reason."

Rainbow shrugged, "Yeah, but what? And why is there still water in it?"

Pinkie perked up, "Ooh, I know! Maybe it's unfinished! Can we finish it?!"

While the others kept talking, Tails examined the area carefully. "These gems that Rarity and Spike are picking up… these normal rocks around the hole… and these wet spots… Was there something here before?" he wondered. Glancing off to the side, he noticed something on the ground he would've missed were it not for one of the glowing lights in the cavern. Moving closer to the discovery, he examined it carefully before looking back over his shoulder and calling, "Hey, guys!" Everyone turned to look at him at that; he said, "Look at this! I found some prints on the ground over here!"

The others came over and looked at the prints he had found. "You're right, Tails! These look pretty recent…" Shining mused.

Sonic looked closer at the prints before saying, "And wet. Did someone fall into the water?"

They all looked further ahead. "Well, whoever made these prints, it looks like they came from deeper inside this cavern," Twilight said.

Sonic spoke, "Well, let's see if they're still around. Maybe they know what this place is." Everyone agreed with that and began following the prints opposite the way they were going, Spike munching on some of the smaller gems Rarity let him keep as he rode on Twilight's back.

It wasn't long after they started following the trail of prints that the group noticed two other paw print trails heading in the same direction. Aside from size, the prints appeared to be very similar to the ones in the trail they were following. They looked more noticeable and wetter than the prints at the spot where the group had started tracking them. Still, no one was really sure who the prints belonged to. Spike and the Main Six thought they looked familiar, but nobody spoke up.

Suddenly, they all heard something from around a corner and came to a stop. "Ooh! Careful, Fido! We don't want to lose the precious gem!"

Sonic asked, "Fido? Who's that?"

Twilight raised an eyebrow, "That voice sounds familiar."

Rarity's face adopted an unusual glare as she said, "It certainly does, Twilight. I'd recognize it anywhere!" She suddenly ran ahead of the group, surprising them so much that nobody tried to stop her. There were surprised exclamations a second later, followed by Rarity screaming, "I KNEW IT WAS YOU, YOU… YOU DOGS!"

Spike placed his claws on Twilight's neck and used his arms to catapult off of her back, the unicorn's head bobbing a bit as he exclaimed, "Rarity!" He dashed ahead of the group, after the mare of his dreams. The others came running several seconds after the shock had worn off to find what would normally have been an amusing sight: Rarity and Spike playing tug-of-war with the three Diamond Dog leaders that had pony-napped Rarity so long ago, only instead of using a rope, both sides were pulling on a large emerald that was about as big as the Master Emerald, Rarity having her hooves wrapped around the bottom with Spike pulling her rear right leg while the Diamond Dogs gripped the top of the gem..

"Put the gem down this instant!" Rarity exclaimed.

"No! Be gone, pony! We found this gem first! It's ours!" the leader and owner of the earlier voice, Rover, said.

"LET GO OF IT!" Rarity shrieked.

"Save it, pony! Your annoying sounds won't work this time!" the large blue dog, Fido, said.

"Yeah, especially not when we have a gem this big to take back!" nodded the short dog, Spot.

Tails watched the spectacle for several seconds before turning to Sonic and asking, "Should we help them?"

Sonic looked back at the exchange. "Maybe, but which side?" he asked after a moment.

Twilight looked at him and said, "Sonic!"

The blue hedgehog shrugged, "What? They look evenly matched to me!"

Pinkie cheered, "Go, Rarity! Go, Spikey! Beat those doggies!"

The struggling continued for a couple seconds more before Spike, Rarity, and the Diamond Dogs all made one final pull, all of them grunting and straining to pull the gem to one side.

And that's when it happened.

While sliding her free leg back, Rarity suddenly lost her balance, causing her to slip and lose her grip on the gem. Both she and Spike fell forward with a gasp while the Diamond Dogs, who were unprepared for this, tumbled backwards with the gem in their paws. When they fell on their backs, the large jewel landed on its top and, to everyone's surprise, broke apart! The pieces of the gem scattered across the ground, moving a bit as they landed before coming to a stop.

Rarity and Spike looked up and gasped while the Diamond Dogs, upon seeing what happened, rolled over and stared in horror. "NOOOOOOOO! Not the precious gem!" Rover cried.

Fido picked up two of the pieces and looked down at them. "How did this happen?" he murmured.

Spot perked up as he said, "Wait! We can take all these gem pieces back with us! Then we'll have lots of gems!"

While they were talking, the others walked closer, most of them moving towards Spike and Rarity while Sonic, Tails, and Twilight moved a little closer to the Diamond Dogs. "How did it break like that? It should've taken more force to break a gem that big," Cadance commented.

Shining nodded, "Yeah. Is there something wrong with it?"

Tails walked over to one of the pieces on the ground and picked it up with his left hand, holding it up to his face and examining it. Spot noticed and said, "You! What are you doing?!"

Tails looked at him and replied, "I'm just examining the gem you found. You do know it's fake, right?"

Rover's eyes went wide, "Fake?! What?!" he cried.

Tails shrugged, "Sure. It's the most reasonable explanation for why it fell apart like that." He flipped his left hand around and let the piece fall to the ground, where it broke once again.

While the Diamond Dogs stared in shock at this fact, Spike looked up at Rarity as she sighed sadly. He stood up and asked, "Rarity? Are you okay?"

The white unicorn glanced down at him and said, "I'm fine, Spike. I just got my hopes up when I saw that gem. Gems that size are so rare; I should have known it wasn't real as soon as I saw it."

Applejack leaned close to the fashionista as she smirked, "Tom musta been pretty big too."

Rarity's eyes widened and then narrowed as she darkly muttered, "How many times am I going to be reminded of that today?"

Sonic, Twilight, and Tails walked over to her and the others, Sonic carrying one of the pieces in his right hand. "Ah, don't take it too hard, Rarity. It does look pretty convincing, even up close," Sonic said. He glanced down at the piece in his hand, "Guess you really got to look close to spot the difference."

Tails nodded at him, "Yeah, kind of like with iron pyrite." Sonic threw the piece in his hand back over his shoulder, the chunk bouncing off the ground before it went sliding backwards.

Shining looked over at the Diamond Dogs, who now seemed to be standing up, and asked, "Should we take them with us?"

Rarity stood up and simply said, "Absolutely not. I refuse to spend any extra time with them."

Sonic looked at her and asked, "Why not?"

Rainbow nodded, "Yeah, come on, Rarity! You reined 'em in the last time we saw them!"

Rarity protested, "After pony-napping me, showing a complete lack of hygiene, and subjecting me to horrid underground conditions, that is. This cavern is so much better than their tunnels, it's not even funny. I wouldn't be surprised if they decided to move here."

While she was speaking, Rover quickly picked up on her tone and, after she finished talking, got up in front of her and said, "QUIET! Don't you start your whining or complaining or whatever you call it again! My ears are still ringing from the last time!"

Fido and Spot stepped up alongside him, Fido saying, "We don't need your spell this time anyway. We've already found plenty of gems here."

Twilight asked, "How did you even get here?"

Spot answered, "Tunnel. We walked down it and it led here. Not sure how, but we soon found gems here. Good enough for us!"

Rarity rolled her eyes, "How positively primeval."

Tails asked, "You guys really like gems, huh?"

Fido said, "Of course! Gems are our life! We're always itching to find more gems!"

Sonic smirked, "You know, there's plenty of water down here. A good bath ought to take care of that itch."

The Diamond Dogs stared at him for a moment before it seemed like a light bulb went on in their heads. Spot demanded, "Are you making fun of us?!"

Sonic glanced off to the side as he replied, "Maybe." He then looked at Rarity and winked, the white unicorn holding a hoof up to her mouth and giggling in response.

Fido growled, "Why, you…"

He was interrupted when Fluttershy let out a loud scream, one that was very clearly heard by everyone present. They all turned to her, Applejack asking, "What's the matter, Fluttershy? Why'd ya go and…" She trailed off as she and the others saw what Fluttershy was looking at.

As they looked into the distance, towards the waterfalls and the cavern wall, it began to change before their eyes. The once tan and brown rocks changed into a mix of yellow and purple lines, the clear blue water seemed to become light blue lines, and the emerald pieces turned into barely recognizable green shapes. And mixed in with the corrupted look of it all, amongst the strange shapes, were a multitude of ones and zeroes.

"What in the world is THAT?!" Twilight exclaimed.

"I don't know, but it looks like its spreading!" Sonic growled. Indeed, what started as a small (from where everyone was standing) spot on the wall was beginning to expand, starting to cover the rest of the cavern.

"It almost looks like it's all being converted to code!" Tails gasped.

Rover turned and started running deeper into the cavern, calling back, "FIDO! SPOT! WE'RE LEAVING NOW!" The two Diamond Dogs quickly turned and did the same, running after their leader.

Rainbow called after them, "Hey, where are you three going?!" Suddenly, the ground began to shake, a nearby rock column breaking off from the ceiling and falling to the ground in front of the path the group had come from, practically blocking it off.

"What in tarnation is goin' on here?! Is this place fallin' apart?!" Applejack exclaimed.

"It's not falling apart, it's being scrapped! Removed! Deleted! And soon we'll be deleted too!" Pinkie gasped.

Spike looked up at Tails, who was looking down at his radar, and waved arms while saying, "Tails, we've gotta get out of here! Get the Warp Ring out!"

Tails continued to look down at the dual screens of his radar for a moment, the readings looking even worse than they were before. It was a miracle it hadn't exploded yet. He then looked down at Spike and said, "Right!" He put his radar away and pulled out the ring, everyone moving away to give him room. He tossed it forward… but nothing happened. The ring stayed the same size and simply bounced when it hit the ground.

They all stared down at the ring in horror. "It's not working?!" Rarity cried.

Tails quickly grabbed it with both hands and held it up to his face, "That's impossible! It's got energy in it! More than enough to teleport all of us! So why isn't it working?!"

Twilight suddenly remembered something and said, "Wait! The Diamond Dogs said they went down a tunnel and ended up here! They must have gone through a portal without realizing it!"

Princess Cadance looked over at her and nodded, "That must be why they ran deeper into the cave! The portal must be up ahead somewhere!"

Sonic glanced back over his shoulder and noticed, just over the fallen pillar, that the strange corruption was spreading along the path they had come down. He looked back at the others and said, "Anything's better than standing around here! Let's go!" They all turned and ran to catch up with the Diamond Dogs, Tails tucking the Warp Ring away and Twilight placing Spike on her back since he was having trouble keeping up.

Sonic and Rainbow Dash took the lead, staying ahead of the rest of the group and keeping an eye out for any signs that the cavern was going to disappear right out from under them. Soon, Rainbow called down to Sonic, "There's a ledge coming up!"

Sonic quickly brought his feet down, sliding across the ground towards the ledge. He came to a stop right at the edge, most of his shoes dangling over open air. "Whoa!" he exclaimed as he waved his arms around trying to keep his balance. After a second, he stepped back and looked down to see he had almost fallen into a pool of water, just inches below where his feet had been.

Rainbow landed next to him, the others catching up as she asked, "Has it already reached here?!"

Tails said, "No, it's still behind us! This is still stable ground!"

Twilight looked down at the water, "Then this would explain why the Diamond Dogs' paw prints were wet! They must've had to swim here!"

Spike spoke, "Yeah, that's great, Twilight, but WE still have to get out of here!"

Shining looked over at Sonic and asked, "Are you going to need some help getting across this, Sonic?"

The blue hedgehog looked back over his shoulder and saw, at the edge of his vision, the corrupted cave creeping up on them. Realizing it would catch up to them soon, he ran over to Rarity and Pinkie Pie and picked them both up, holding them above his head as he ran out onto the surface of the water while saying, "No time for swimming lessons!"

Rarity gasped and tried to keep herself balanced while Pinkie cried, "Wheeeeeeeeee!" at being ferried in this manner.

Everypony looked briefly surprised at Sonic's ability to run on top of the water, but Rainbow soon said, "Can't argue with that!" She spread her wings and took off, grabbing Applejack with her hooves and flying after Sonic while Fluttershy took Spike, Tails grabbed Twilight by her sides, and Cadance combined her magic with her husband's to carry him.

Sonic soon reached the other side of the pool of water and leapt onto dry land, stopping and setting Pinkie Pie and Rarity down on their hooves. The others soon caught up and set their charges down before they all took off running again. It was all flat ground now, and they could see a light coming from up ahead. Sure enough, it was coming from a portal at the end of the cavern and they all leapt through it just about together, leaving the doomed cavern behind. The portal closed after they were all through and shortly afterwards, the corruption caught up and claimed the entire cavern…


The group lay sprawled out on the ground of… wherever they had ended up, all panting and trying to catch their breaths, the portal they had come through having already closed. Even Spike was lying on the ground, panting as the adrenaline in his system thinned out. Eventually, everyone managed to sit up, no one really ready to stand back up again. Twilight sighed, "Well, we made it… That was crazy…"

Applejack, who was next to her, nodded, "It sure was, Sugarcube." She then looked around, "Where are we now?"

Cadance looked up and said, "It looks like we're still underground somewhere."

Shining looked up and off to the side, where he spotted something interesting. "Is that a… castle?" he asked. Everyone looked up where he was looking and saw a large stone structure with two large torches on the top of the front towering over them. In front of them was a set of stairs leading up to the entrance to the building.

Sonic spoke, "Hey, I recognize that. That's Angel Island's Hidden Palace."

Twilight looked over at him and asked, "Angel Island? You mean Knuckles' home?"

Sonic nodded, "Right. After the Death Egg crashed on the island, Knuckles moved the Master Emerald from its shrine down here to keep it safe while he dealt with the 'intruders'. Eggman ended up finding it after the Death Egg crash-landed again, this time on top of this mountain."

Fluttershy asked, "We're in a mountain right now?"

Tails nodded, "Yeah. Look up there." He pointed up and everyone followed his finger to see a hole some distance away from the roof of the Hidden Palace. Light appeared to be coming down through it. "That light is coming in from the outside. When it crashed, the Death Egg's face poked down through that hole," Tails explained.

Twilight asked, "Wait, if there's a hole up there, are we inside a volcano?"

Sonic replied, "Technically. The Hidden Palace is surrounded by the Lava Reef Zone, which acts kind of like a final line of defense for anyone who comes down here. Nothing to worry about, though; we're past the reef and I'm pretty sure it keeps the mountain from erupting. We're cool."

While he was talking, Tails had pulled out his radar and was examining it. After a minute, he spoke up, "Those weird signals I picked up earlier are starting to clear up." He moved his radar towards the Hidden Palace and said, "It looks like they clear up closer to the Hidden Palace. If we go in there, we might be able to use the Warp Ring to get out of here."

Rainbow Dash spread her wings and flapped up off the ground, saying, "Well, let's get in there, then, before something else weird happens!" Everyone stood up and began making their way towards the palace, the walk up the stairs seeming very relaxing after the potentially death-defying run they all just had (except for Rainbow, who hovered over everyone's heads as they went up instead). At the top of the stairs, they went through the archway and, after dodging a pair of flame traps near the entrance, went down the hallway leading into the palace.

The hallway emptied out into what could be considered the palace's lobby. Off to their left, the group could more clearly see the light coming in through the hole at the top of the mountain, though it still looked far away. As they walked down the stairs, Rarity commented, "For such a 'hidden' palace, this is really quite elegant. And it still appears to be in one piece as well. I am quite impressed."

Cadance looked at Sonic and asked, "Did you think it was amazing the first time you came here, Sonic?"

Sonic looked back at her and shrugged, "Eh, I guess it kind of went over my head at the time, Cadance. I ended up getting knocked down closer to the lava down below, so after getting across that, I came in through the lower entrance. Not quite as nice a view from down there. Plus I'd just tangled with Eggman, so I sped through here to see if he'd gotten inside the palace yet."

Cadance replied, "Oh. Well, at least you get the chance to see it now!"

By this time, they had reached the bottom of the stairs and were now walking towards the center of the room. As they reached the center, they all noticed the raised platform there, along with the device sitting in the middle of it and the small, circular roof that had a circular opening in the middle above it. "What's this?" Twilight asked, looking at the red device on the platform.

Sonic answered, "That's a teleporter. I used it to get up here from the bottom level, but it can also be used to reach the Sky Sanctuary." He took a closer look at it before saying, "Looks like it still works, but it probably doesn't go anywhere now, seeing as the Sky Sanctuary was mostly destroyed after Eggman used the Master Emerald to launch the Death Egg."

Tails nodded, "And then the rest of it was destroyed when Knuckles fought that Mecha Sonic robot in what was left of it. So either it won't activate now, or it just leads to open air."

Spike shivered, "That doesn't sound like it would be fun."

Rainbow spoke, "Yeah, yeah. Can we leave yet, Tails?"

The fox glanced down at his radar, which was in his left hand, and said, "We're almost in the clear. It shouldn't be too much farther." He turned and continued walking in the direction of the emerald altar, Sonic and the others following him.

After passing through the archway, the group walked past several columns as they continued on towards the altar room. While they were walking, Shining Armor looked up to his left, where he spotted something that caused him to stop and say, "Whoa." Everyone else came to a stop upon hearing him and looked up to see a large mural spread across the wall. "Is that tapestry showing…?" Shining wondered.

"It looks like it's showing Super Sonic squaring off against Eggman for the Master Emerald," Tails noted.

Sonic crossed his arms, "Huh. I forgot that was up there. Still have no idea who weaved it, though."

Pinkie looked over at him and tilted her head to the side as she asked, "So you saw it the first time you came here? Which means it's been here for like a really, REALLY long time?" Sonic nodded in response.

Applejack looked at him and said, "Some blanket predictin' you'd fight against a total lunatic and then bein' totally right… Well, ain't that the weirdest thing?"

Sonic looked back at her and shrugged, "Eh, I've seen weirder." After a few moments, the group turned and continued on towards the deepest known part of the Hidden Palace.

After about a minute, the group arrived at the entrance to the emerald altar, the Master Emerald's altar directly in front of them in the center surrounded on the sides by seven pedestals. "Ooh, pretty!" Pinkie said.

"Is this the altar? Where's the Master Emerald?" Twilight asked.

Sonic explained, "Knuckles doesn't keep it down here anymore, Twilight, since Eggman knows where it is. Guess he figured it's easier to keep an eye on it at its old shrine than down here or something."

Tails walked towards the altar, his eyes looking down at his radar. As he reached the front of it, he came to a stop and looked down at the dual screens for a moment. He then smiled, "Hey, it's all clear now!" He reached into his tails and pulled out the Warp Ring; tossing it forward, the ring quickly expanded with a *PHVWOW*. Tails pumped his fist, "All right! We're good to go!" After a quick celebration, everyone stepped into the Warp Ring's center, the ring shrinking down and vanishing after everyone was through it.


Reappearing close to where they had stopped the train, Sonic, Tails, Spike, and the ponies looked towards the front of the train to see the original portal they had gone through was beginning to vanish, the image on its surface completely clouded. After only a couple of seconds, the portal collapsed in on itself and disappeared entirely.

Sonic scratched the back of his head with his right hand as he said, "Well, that was a weird venture, but at least that portal's no longer in the way."

The others, except for Tails, agreed with him, Spike saying, "Yep! So it's a straight shot to Canterlot from here on out, right?"

Tails spoke up, catching everyone's attention, "Uh, I don't know about that, Spike. Take a look at this, guys." Everyone walked over to Tails and looked around him to see that the fox was looking down at his radar again. The bottom screen was displaying readings while the top screen showed the map, currently set to show the train's path to Canterlot. Looking at the top screen, they could see that several blinking dots had shown up on the map. And as they watched, even more dots began to appear…


Wow. I finished this first chapter WAY later than I intended to. I wanted to have it done in time for MLP: FiM's season four premiere, but it was not to be. Well, at least I got it done in time to kick off the proper Christmas season in a way.

I know some people wanted to see the Diamond Dogs fight Sonic and the others, but even if it continues from a certain point in the main story, I didn't want to kick this story off with a rival battle. I mean, I wanted the Diamond Dogs to appear here; I just didn't want them to fight with the group or just have a background appearance. Also, the Diamond Dogs did not use the same portal the group did to escape the Sonic 2 Hidden Palace; they used a different one that was close to the one the group used that takes them back to their tunnels. They were just gone by the time the group arrived and their portal had already closed.

So let's see. Notes, notes...

The first place the group goes, the infamous "Sonic 2" Hidden Palace Zone, I put together based on videos from the Sonic 2 Beta and the finished version of the zone that appears in the hack "Sonic 2 Long Version".

The gem that the Diamond Dogs find is the same large gem that appears in the Hidden Palace Zone. The fact that it breaks when it hits the ground is due to the fact that it was meant to be a breakable object similar to the breakable objects found in the Hill Top Zone (this was not implemented yet in the beta Sonic 2, but it was in "Sonic 2 Long Version"). Tails saying it was a fake gem is meant to make it seem a little more likely that it would break apart.

When the Hidden Palace Zone is being 'corrupted', it's a reference to how the Hidden Palace Zone appears in the final version of "Sonic 2" if it's accessed with a Game Genie.

The appearance of the "Sonic 3 & Knuckles" Hidden Palace from the outside is based on how it appears in the Archie comics, as is the appearance of the emerald altar. Everything else looks like it does in the game, including the mural.

I think that's it. Sorry for keeping you all waiting and I hope you all thought this was a good way to start things off. Hope to have more done soon!

Music:

Relaxing Train Ride... or Not - Sunset Park Classic - Sonic Generations Remix (NicoCW)

A Truly Hidden Palace - The Palace That Was Never Discovered (Hidden Palace Zone Remix) (RikkiSho)

Diamond Dogs! - Super Ponybeat - Diamond Dogs (Euro Dirt Mix) (Eurobeat Brony)

Unplugged - Run! (Final Fantasy IX)

Taking a Breather - Lava Reef (SuperChaosControl)

Hidden, But Not Forgotten - Hidden Palace Zone Classic - Sonic Generations Remix (NicoCW)

Not So Simple After All - Dr. Eggman [All-Star Theme] (Sonic & All-Stars Racing Transformed)