In the throne room, Midnight, Shining Armor, Sunburst, Starlight and Astral stood in front of Twilight, who had a marker board and poster board set up, along with a table that had papers and files on it.

"Alright, Twily, we're here," Midnight said, "What have you found?"

"First, the victims," Twilight levitated photos of the dozens of victims afflicted by the bombs and magicked them to stick to the poster board.
"After examining them further, I'm afraid I discovered that they're not improving... because the effect that drained them of their positive emotions is still active!"

"How did you figure that out, Twily?" asked Shining Armor, troubled by this news.

"Cadance tried to help one of the victims by giving her love energy with her magic," explained the lavender alicorn with a concerned look.
"She didn't even respond! This allowed us to determine that although the victims can still feel positive emotions, it's all quickly drained away almost immediately so it doesn't even register in their minds.

"Which lead me to my conclusion that the effect of those bombs is still actively draining the victims' positive emotions."

"We have to find a way to undo this and help those ponies!" urged Starlight, who hated feeling helpless.

"We will, Starlight," Sunburst gave her a comforting nuzzle, "But our best shot of doing so is finding the changelings responsible and stopping them! If we could just determine where their hideout is located..."

"Actually, I think I can help with that," Twilight brought up while levitating a folder, "The investigation has shed some promising evidence!

"It seems at the locations of where each bomb exploded..." She brought out a photograph that depicted what resembled a manehole in a street, "there was a hatch that leads to some underground catacombs! That has to be how the changelings got in and out without being discovered, and why we still can't find them.

“In fact we know at least two used those hatches to escape into those passageways because we found traces of changeling gew inside of them."

"I know about those catacombs!" Astral took a look at that folder and its contents, facepalming, "I studied the layout of the Empire, including these catacombs for my job working here! I should have known that's how they got in and away..."

"After all this excitement? I could forget something like that as well, Astral," Midnight said while giving the drake an assuring pat on the back, "Don't beat yourself up."

Astral nodded with a sigh and Midnight said to everyone, "We were actually discussing the changeling hideout before you called us, Twilight. This is a major clue which supports my theory that the changelings have to be somewhere underground.

"They'd need to be somewhere safe, sheltered and warm, because they lack the ability to shiver, which makes them more susceptible to extreme cold."

"And the catacombs enable them to get almost anywhere in the city undetected in order to set up their attacks!" Astral added. "Not only is it the perfect place to hide and move about with impunity but they can set up traps and ambushes down there in all those winding paths. Unless you know where you're going, you can get lost down there for days!"

"So we're going to need a way to narrow our search for the hideout and a way to avoid any traps or other surprises they may have down there..." Midnight considered before asking, "Would Thorax be willing to help?"

"That's up to him," Shining Armor replied before addressing a guard present, "Go ask Thorax to join us here in the throne room, and assure him he's not in any trouble but rather we need his help."

The guard nodded and left the throne room while Twilight unrolled a map of the Crystal Empire and gestured everyone to join her at the table to look it over.
"Nine places were bombed, each of them with a hatch that leads down into the catacombs. Look."

Her horn lit up and markers levitated over the map and then marked the mentioned bombsites and then started drawing numerous lines all over and around the city, and then some of those lines extending towards the outskirts and one beyond the perimeter of the Thermal Barrier.

"These lines mark the catacombs based on maps and documents in the Empire Archives," explained Twilight. "I sent word to Captain Firestorm to inform him of every single hatch throughout the city and he's coordinated with the Praetorian Guard to have at least two guardsponies stationed at every single one.

"The changelings won't be using them again as they did before."

"Hopefully, that will at least discourage them from making their next move for the time being," considered Midnight before adding, "Meanwhile, it's time for us to prepare our team!"

"Uh, team?" Sunburst gave his master a slightly nervous look.

"Shining, Sunburst, Astral," Midnight looked to each of them, "I propose that we venture into the catacombs, find the bugs' hideout and clean up house! We'll need Thorax with us in order to get a good idea of what we may encounter, but I understand if any of you-"

"I'm in," Shining Armor said without hesitation as he summoned his sword.
"...So am I!" Sunburst couldn't deny he was afraid but his sense of duty, as well as his desire to make his mentor proud, spurred him to summon his own sword too.
"I'd follow you straight into Tartarus, sir!" Astral conjured his twin swords.

Midnight smirked, glad and relieved, as he summoned Nightfall and raised his sword up and they did the same with theirs.

The doors to the throne room opened and they looked to see Thorax timidly walk in, in his "Crystal Shade" persona, and ask, "Um... am I interrupting anything?"

"C'mon, Cora, watch me!" Spike sat in front of his honorary niece, Cora, trying to show her the motions. "Pat a cake, pat a cake, baker's mare... Bake me a cake with loving care..."

"Pabba ca, pacca?" Cora babbled with infantile confusion, finding it hard to follow the motions her Uncle Spike was trying to show her.

"Close, but let's keep trying," Spike chuckled when he noticed Elytra wasn't participating.

The changeling filly sat aside, holding a stuffy that looked like a cute little caterpillar and kept glancing at the door. Outside said door were two guards, assigned to protect the Little Princess along with her favorite sitters, Thorax and Elytra. But Thorax had been called away and returned a little while later to tell his little sister that he needed to help with the big problem going on, and asked Elytra to stay in the nursery with Cora and Spike, where they would be safe.

Elytra understood Thorax was needed, but she was so worried. Despite their freedom, Elytra herself remained connected to the Hive Mind despite all attempts to sever her connection to it. Most days, she went without hearing so much as the slightest buzz of telepathic static, due to her being so isolated from the rest of the Hive. But lately, the static had grown louder, more frequent, and now she was occasionally picking up faint telepathic conversations, only able to make out a few words now and then.

It'd been further confirmation of the changelings being behind this big problem, and though Elytra offered to help, Thorax, Cadance and Shining Armor wanted her to be safe and had her stay with Cora in the nursery.

"Elly?" Elytra looked back at Spike, unable to crack a smile at the nickname he'd given her as he asked in concern, "Are you okay?"

"...no, Spike. I don't think I am," Elytra sighed as she closed her eyes, "I... it's hard to explain, but... well, I'm scared! Not just for me, but for Thorax, Shining Armor, Cadance, and especially Cora."

Hearing Elytra say her name, Cora turned to look at Elytra and crawled over to her, giggling at the changeling filly as she grabbed Elytra's hoof and gave it a squeeze. Elytra felt her heart melt with love as she felt the pure and innocent love Cora felt for her, and that made her both happy and ashamed.

"I'm still young and little, but I know more than Thorax thinks I do," Elytra put on a smile for Cora's sake, "The Hive... is not a good place for any of the changelings. Mothe- Queen Chrysalis... she doesn't love any of us. Not really... we're just extensions of herself and her power, slaves with no true identity or right to call our lives our own.

"We are taught that our individual selves don't matter. Only the Hive matters, and the Hive survives by serving the queen without question. Even if our orders would... would hurt us."

"But you're free now! You're safe here," Spike assured, coming over to sit beside the two fillies, and putting an arm around Elytra's withers, "They can't hurt you anymore."

"Can they, Spike...?" Elytra felt her emotions bubbling up inside her as she struggled not to cry, "I'm still connected to the Hive Mind! The changelings have come and they've already hurt the crystal ponies! Oh, Spike, I... I wish... oh, why couldn't I have been born a pony instead of a changeling?!"

Elytra couldn't hold back the tears anymore as she began to cry, burying her face into the caterpillar stuffy, and Spike hugged the filly close, as well as his niece as Cora began to get upset that Elytra was sad.

In Shining Armor's Study, he, Midnight, Sunburst, Astral and Thorax stood around a table with the map of the catacombs before them as they planned their strategy. Thorax was already briefed on what was going on and so they needed his input on this.

"Well, as Midnight said, changelings need someplace sheltered from the cold, somewhere safe but in this case they need a place that's... strategic for them," Thorax ran his eyes over the map. "So, it'd be best for them to hole up somewhere that's not directly underneath the empire. Too risky to be that close."

"So then... they're most likely based in one of the catacomb tunnels that extend to the outskirts or even past the perimeter of the Thermal Barrier," Astral pointed out said catacombs on the map. "There's five altogether."

"But... only one of them extends past the perimeter," Shining Armor pointed to it, "This one, to the south-east."

"Shining, can the Crystal Heart alert you when uninvited guests step through the barrier into the Empire?" asked Midnight.

"It gives off a special resonant sound and glow whenever anyone steps in or out of the barrier's perimeter," Shining Armor confirmed. "We have an office in the Praetorian Guard that keeps track of those comings and goings to determine which are scheduled and which are not."

"Have there been any unscheduled or unsanctioned crossings in or out of the barrier in the past few days?" asked Midnight with a raised brow.

"I get where you're going with this, Midnight," Shining Armor considered, "I'll have to check with the office, but they normally keep me, Cadance or our closest advisors informed of suspicious traffic through the barrier."

"Assuming there isn't any," Midnight pointed to the catacomb tunnel that extended past the perimeter, "then this must be how the changelings have infiltrated the Empire without raising any alarm!

"It's the only way in and out of the city without passing through the barrier and the Heart detecting it."

"I feel I should point out something," Sunburst spoke up, "Given the Heart's current malediction, it's possible it may be unable to sense traffic through the barrier and inform us of said traffic."

"Which makes putting a stop to these invaders and saving the Heart and citizens all the more precedent," added Astral in agreement.

"Sunburst, can you see the closest access point to that tunnel?" asked Midnight.

"I'll find it and memorize the catacombs' network of pathways to be sure we don't get lost," Sunburst took the map and began to study it.

"I volunteer to be Thorax's bodyguard," Astral raised a claw, "So far, we've kept the instigators being changelings under wraps from the citizens, but if they find out somehow there's a chance they'd do him harm out of accusation."

"Thank you, Astral," Thorax smiled with bittersweet appreciation. Although he and Elytra had been embraced by the Empire, there were still a few bigots here and there that weren't exactly subtle in their opinions regarding changelings.

"In the meantime, let's prepare for our expedition into the catacombs and inform the girls," Midnight suggested to Shining Armor.

"Right. If we took off without telling them, we'd be in for it," Shining Armor chuckled with just a hint of apprehension.

Which got him and Midnight a 'Wa-pish' from Astral as he made a teasing show of whipping his tail. In response, Midnight used his magic to pull Astral's hood over his head, causing him to cry out, "Hey!"

Entering the nursery, Thorax and Astral both smiled to see Spike was sitting on the blanketed floor, Princess Cora snuggled up to his warm tummy and napping peacefully while Elytra looked at the filly with warm eyes.

She noticed them and her eyes lit up before remembering and she quietly held a hoof to her mouth and pointed out Cora napping. Spike gently waved at them, not daring to move and disturb his honorary niece.

Thorax gestured Elytra to follow him and she did so, stepping out of the Nursery and into the hallway with Thorax and Astral. Astral kindly asked the guards to give them a moment to talk privately and they walked away but kept at the opposite ends of the hall, ready to resume their posts.

"What's going on?" asked Elytra, gazing up at her big brother.

"Elytra, we... we're going to go find the changelings that are hurting the crystal ponies," explained a hesitant Thorax. "Prince Shining Armor and Midnight Blaze asked me to come along and help."

Elytra's face turned to fear as she shook her head, "No! Don't go!"

The changeling filly quickly hugged Thorax, almost desperately, surprising him and Astral as they shared a bewildered look. Thorax gently hugged Elytra back and said, "Hey, hey! It's okay, Elytra, we'll be fine."

"I give you my word, little filly," Astral knelt down and comforted Elytra with a soft pat on her head. "I'll protect your brother and have his back."

Elytra gazed up fretfully at the dragon and said, "It's... I have a bad feeling. I've... I've heard buzzings."

"Buzzings?" Astral didn't get understand, but thorax did.

"She means the Hive Mind," Thorax answered, "Elytra's still connected to it, but since we're so far up north and isolated from the rest of the Hive it hasn't bothered her aside a few dreams. What is it, Elytra? What have you heard?"

"Nothing clearly, just... a haze and-and noise," Elytra held her head with a hoof, "The other changelings who've come aren't close enough for me to hear them clearly through the Hive Mind.
"But... earlier, I heard- No... I saw something in my mind, something... strange."

"What was it?" asked Astral.

"I don't know, a... a lion? A snake? But then I heard some kind of... bleating," Elytra explained apprehensively. "It sorta reminded me of the ewes at the petting zoo we visited last week."

Thorax and Astral shared a confused look, but both shrugged, not getting it either.

Sighing dejectedly, Elytra whimpered, "You don't believe me..."

"No, no, little sis, we believe you, I promise," Thorax assured her before clarifying, "We're just... confused, like you."

"A lion, a snake, and the sound of a sheep bleating?" Astral pondered a moment, "It... sounds familiar, but I just can't put my claw on it."

"Astral. Thorax." They all looked down the hall where they saw Midnight, garbed in his cloak. "It is time."

Thorax and Astral nodded to him, and they looked at Elytra again, Thorax saying, "It's time for us to go, Elytra. Stay in the nursery with Spike and Cora. You'll be safe, and Cadance will be by later to check on you all, so be a good little wuvbug, okay?"

Elytra gave her brother such soulful eyes it darn-near broke his heart, even though she nodded and they hugged again. But it was in that moment, she spoke to him so softly that only he could hear her, "Thorax... he's here."

Thorax was glad his back was to Astral, because his eyes widened in understanding and worry. He let go of his little sister and quietly prodded her back into the Nursery. Astral gave Elytra another assuring pat on the head and a wink before he closed the door, even as Elytra stood there, afraid for her brother and hoping he'd just come back safe and sound.

In the courtyard, with a perfect view of the infected Crystal Heart, the group, armed and equipped and prepped for their mission, had a quick word with Twilight, Starlight and Cadance. The princesses nuzzled their husbands while Sunburst and Starlight had a moment as well that included a tender kiss for luck.

Thorax felt the love shared between the stallions and mares, and strangely found himself not hungry for it. This would have baffled him were it not for Elytra's words as he thought, What am I gonna do if I see you... brother?

Astral stood at the ready, arms crossed, his swords strapped to his back, as he patiently waited. He then noticed Cadance come over to him with a worried look, causing him to salute.
"Worry not, my princess. I'll be sure your husband comes home to you safely."

"You take care as well..." Cadance gave him a teasing look before saying, "Pie Splatter."

Astral's eyes nearly popped out of his skull as he quickly responded, "SHHH-Shh-sh-sh-shhhh... Cadance, if I've told you once, I've told you a millions times! Never call me that in front of anypony who doesn't kno-"

"Oh Shining already knows," Cadance interrupted with a trollish smirk.

"Ergh! Stupid loopholes..." the embarrassed drake uttered under his breath while facepalming. but then he playfully glared at the pink princess, "Sometimes I wonder if you've hung around your aunt too much."

"Who, me? Never," Cadance said, playing innocent.

"There's a reason you barely got a passing grade back in drama class, Cade," Astral raised a brow and smirked while crossing his arms, clearly not fooled as he rolled his eyes.

Cadance giggled before pulling astral in for a hug, and whispering, "Be careful" into his ear.

He hugged her back and said, "Aren't I always?"

"Alright, guys!" They broke the hug to see Midnight and Shining Armor standing together as Shining said, "Time to move out!"

The princesses and Starlight watched as their stallions and two good friends ventured off, side by side, looking oddly heroic, not needing to look back because they knew they were going to come home to their loved ones without a shadow of a doubt.

"Say Astral," Midnight asked out of nowhere, "What was that about pies you were discussing with Cadance?"

Astral groaned to himself as he began to plan diabolical revenge on his old schoolmate.

The group made for a hatchet that was located close to the edge of the city, as Sunburst explained the catacomb beneath it was the closest route to the one that led to the catacomb that extended all the way past the perimeter of the Thermal Barrier.

Once all five of them had dropped down into the dark depths, Midnight, Shining Armor and Sunburst illuminated their horns while Astral breathed a small fireball into his hand and Thorax lit up a special changeling gew lantern he'd made, which provided a modest glow.

They looked towards the catacomb, which was constructed of both stone and crystal, and found it to be dark and chilly.

"In case it's not obvious," Shining Armor said as his feathers shivered, "but this places gives me the creeps."

"Yeah, I've got a bad feeling about this...!" Thorax gulped.

"Oh come on, guys! It's just a catacomb built directly under the Crystal Empire," Sunburst assured, sounding oddly optimistic, "Just think of the history!"

"Speaking of," Astral interjected as they started walking down the tunnel, "Why exactly are these catacombs beneath the city? Did Prince Sombra construct them when he was still the Crystal Empire's king?"

"He did. I sent a message, asking him about these catacombs," Midnight answered, "He built them in case of emergencies, as well as to provide additional shelter to the citizens in times of crisis.

"As a matter of fact, this catacomb we're looking for, it was meant to be an emergency escape tunnel to get the crystal ponies out of the empire without being seen by enemies."

"Well, unfortunately, it's allowed my former hive mates access into the empire," Thorax sighed woefully. "If only there was a way to free them from the Hive Mind, like me. They could see there's a better way, to earn love and friendship rather than steal or lie to get it."

"We'll keep trying to figure it out, Thorax," Shining Armor assured his friend. "Cadance and I did it for you, we'll find a way to do the same for other changelings. Starting with Elytra."

Thorax smiled gratefully at Shining Armor when Midnight asked, "So, Shining, how's it been, trying to learn more about your sword?"

Shining Armor responded by summing said sword to his hoof. Its blade was adamant and crystalline while the handle was cobalt blue with his cutie-mark on the crossguard.

"It's a fine weapon," Shining Armor admired it, his eyes noting every detail, before he sighed and absorbed it back into his body. "But I haven't figured out how to tap into its powers."

"You never know, Sire," Astral gave Shining an encouraging smirk, "That day could be today! All you need is the right motivation and perhaps some inspiration."

"If it makes you feel any better," Sunburst brought up, "I haven't had any luck with my own sword either."

"It's possible the Map back in my and Twilight's castle will call upon you," Midngiht suggested, "To send you somewhere where a wrong needs to be righted.

"That's how it worked for the rest of the Knights of Harmony. Although in my case, it was facing a corrupt businesspony who staged a coup and outbreak of poisonous food."

"Well, I'm sure the powers of our swords will reveal themselves when the time is right, eh Sunburst?" Shining Armor shrugged in good nature.

"Most likely. All the same, I believe my spellcasting skills will serve me better," Sunburst responded wit ha confident smirk. "Midnight has really been helping me hone my magical pr-OW!"

Sunburst stumbled forward, falling onto his belly, the others stopping and looking to him in concern as Midnight asked, "You alright?"

"Yeah! Ergh, I... I think I tripped in something," Sunburst propped himself up and looked at his hoof... to see it was steeped into something pale green, viscous and sticky.

Gasping, Thorax gave it a close look and a sniff before confirming, "Changeling gew, less than a couple hours old."

"it seems we're on the right track," Midnight narrowed his eyes as he gazed down the tunnel... and then let out a droning hum sound. His ears perked as the sound carried down the catacomb, but nothing echoed back.

Opening his eyes, he looked to his friends, saying, "The way is clear for quite a long distance. I didn't detect anything alive further in."

"Then let's keep moving, "Shining Armor took point, "but take care. The changelings could be anywhere. Or anything..."

They sallied on, keeping an even pace as they ventured further and further down the tunnel. The distance made sense, as this catacomb was supposed to reach all the way past the empire's perimeter. After walking for nearly an hour, Midnight had them pause once more so he could use his echolocation again.

His ears perked at what he sensed, and Astral quietly asked, "What is it, sir?"

"...Ahead, about another fifty yards," Midnight pointed onward, "the tunnel opens up into a large chamber, with multiple passageways."

"Strange, that wasn't in the maps or records regarding the catacombs beneath the empire," Sunburst was confused. "I went over them backwards and forwards while memorizing them."

"It's possible Sombra constructed something else in these catacombs but left them out of the records and maps intentionally," Midnight suggested, "I know I would, if I was going to design a network of secret passageways."

"We're gonna have to talk to him about these catacombs once this is over with. C'mon," Shining Armor took point again, and eventually they came to the chamber Midnight had sensed via his echolocation.

It was a vast space, round with a spherical ceiling that had a HUGE crystal set into the middle of the ceiling, and judging from the light glistening through it it must have reached all the way to the surface. Said light gave the chamber enough visibility to show the group that there were four passageways equidistant from each other and the one they'd just come in through.

Cautiously, the five walked in and around as they gazed upon this ancient architectural marvel, Midnight speaking softly, "This room is old. Very old..."

"Yes, it is!" Sunburst examined the walls and saw carvings of pictograms that reminded him of the artistic style he'd seen in the Crystal Empire. "Judging from these pictograms and the stone used to construct all this, this place is surely over a thousand years old! Perhaps even older than the Empire itself..."

"But didn't the Empire vanish into thin air for an entire millennium and come back the same way it was when it left?" Astral pointed out. "Wouldn't this place be the same way?"

"Not unless it didn't vanish with the Empire back then," Shining Armor considered, "Since this place is outside the Empire's perimeter, it might not have been affected by the curse that made the Empire vanish. So it remained here, completely lost and forgotten until the Empire came back."

"Sombra had to have constructed this place," Midnight gazed up at the giant crystal in the ceiling, "I sense his magic woven into these very walls."

"Well, in case you're all wondering," Thorax spoke up as he dared to get a little closer to the other passageways in the chamber, "I believe a changeling has been down each of these tunnels, but I can't be sure where they are now."

"Midnight?" Shining Armor looked to his brother-in-law.

"On it," Midnight stepped forward, took a breath... and let out another droning hum, using his echolocation towards the passageways.

They waited patiently as Midnight listened... and his eyes opened before he turned to them and said, "Two of these passageways lead to the same room, one goes upwards, so I believe it may go all the way up to the surface."

"That might be the way the changelings got in here and then into the empire," Shining Armor pointed out.

"What about the other two?" asked Astral.

"One curved around, I think it may lead back the same direction as the tunnel we came," Midnight answered, before he pointed to the tunnel that was directly in front of them, located opposite from the one they'd came in.
"This one... leads further way, so far that I couldn't sense anything else down there."

"Hmm, that tunnel has more traces of changeling gew in it than the others, except for the one that could lead to the surface and the one we came here through," Thorax brought up.

"Then that's the tunnel we have to take," Shining Armor furrowed his brows, "Onward!"

They were about to enter the tunnel when all of a sudden they heard a loud and harsh insect-like buzzing! The kind that came from an angry swarm of bees.

Or changelings! Thorax realized when they heard a dark chuckle echo through the buzzings and from all around them as a voice Thorax hadn't heard in a long time spoke but two words that filled him with dread.

"Hello... brother!"

Next Chapter: 394. Crystal Quest - Part 4 Estimated time remaining: 11 Hours, 40 Minutes