“How far do you think it is to the bottom?”

“Why don’t you throw something in and find out?” Valor chuckled.

Firefly continued to gaze into the maw that yawned before her. The mineshaft was even more enormous when viewed from the ground, being dwarfed only by the ship that was parked atop it. Tiny points of violet sparkled along the walls, slowly tapering off as they went deeper. Firefly wasn't about to count them all, but even if she did, she knew she'd lose them in the utter darkness below.

“I have a half a mind to throw you in, Valor,” Firefly sneered in mock derision, concealing her discomfort behind snark.

Vertigo was never a problem for Firefly. She was a seasoned combat flier and a war veteran. She’d endured storms on airships, high-G maneuvers during combat, and being hit with enough shrapnel and concussions to break a pony several times over. But looking into that nigh-bottomless pit made her stomach churn. Perhaps it was the ingrained fear of the unknown that plagued all herd animals. Perhaps it was the unearthly silence that seemed to absorb all sound that fell into it. Maybe she was just on post-combat adrenaline jitters. Whatever it was, Firefly was on edge.

“Why?” The stallion laughed, the smoke from his cigarette blowing out his nostrils. “So you don’t have to buy my drinks tonight?”

“If I remember correctly, I held up my end of the bet,” Firefly said matter of factly. “Your boys and girls arrived without so much as a scratch.”

“Ah,” Valor countered, “but I still got to kick griffon ass. I do believe it was my ship that took down the Kestrel?”

“And who set up that shot for you?”

“Thunderlane, of course. Perhaps you should buy him a drink, too!”

“Oh no, I’m not encouraging that boy to follow my hoofsteps. He’ll get himself into trouble and then where would you be?”

The Abyss was like an airship crash. It was unnerving, unsettling, and ultimately terrifying, but once it caught the eye there was no escape from staring. Even while speaking with Valor, Firefly had to resist the urge to turn and gaze into it. She’d never let him know it, but Valor’s silly banter was providing a much-needed distraction.

"How about we call it even then?”

“You mean we buy each other drinks at the Horseshoe when we get back to Crystal Spire? What kind of panzy-ass deal is that?”

“I was trying to be diplomatic.” Valor paused to take a drag on his cigarette. “You really aren't going to buy your pal Valor a drink?"

To be fair to Valor, he was starting to grow on Firefly. His glibness was a refreshing break from inter-squadron politics and what had begun as meatheadedness had quickly sorted itself out to be humor rife with irony. It was something Firefly could accommodate and in addition deal back in spades. This was the beginning of a beautiful friendship.

“Nope.”

“Harsh.”

“Take it or leave it. ‘Cuz if you don’t I’ll have to kick your ass.”

“Is that all you do?” He snorted, crossing a front leg over the other.

“Mmm," Firefly paused for a moment, suddenly adopting a softer, coyer tone. "It's not all I do, but it’s what I usually advertise.”

To her delight, it was enough to get Valor's attention. The brawny stallion gave her a solid look, raised a single eyebrow, then chuckled lightly as he shook his head. “I’ll hold you to that, Firefly.”

She smiled. “Looking forward to it.”

Suddenly, Valor raised a hoof to his earpiece. Firefly heard the muffled chatter of radio traffic. “Sorry, doll, gotta trot. Need to brief my team for the next op.”

“See you at the bar,” she smirked.

The bit of joy faded when Firefly's earpiece buzzed. “Timberwolf, this is Storm Warden. You're needed at the landing pad.”

Now it was her turn. Firefly sighed and began the trot to the makeshift landing pad. The Titan’s Keeper was now a fortified Alliance position. The guns had been manned by Equestrian Army soldiers and Aquellian Marines and the beginnings of a forward operating base were beginning to take shape in the oasis. Firefly could hear chatter and hoofsteps as combat teams continued to sweep the ship for stowaways and intel. The only place that remained unsecured in Azura was the Abyss itself.

Firefly found her squad waiting for her. They formed up quietly in single file just outside the Maresden matting of the improvised landing pad. In moments, their guest arrived from the blue. The corvette's aetherjet engines flared brightly at the last minute to slow its descent, bringing it to a soft landing on the packed dirt and steel grating of the pad.

“Who do you think it is?” Thunderlane asked.

“OGA,” Sunburst spat. “I can smell the sliminess from here. Can't you?”

The drone of aetherjets tapered off as the ship powered down. Firefly noted the paint scheme and tail numbers, or more precisely, the lack thereof. The ship was entirely unmarked, painted a dull storm grey over its entire hull. This was no standard courier or military vessel. With a loud CLUNK, the main hatch swung open.

“Called it.” Sunburst’s pronouncement rang out as the first pony stepped off the ship.

The pegasus mare wore a Royal Equestrian Army combat uniform, impeccably pressed and improbably clean after having debarked from a combat airship. Her coat was a stark white. Only her fetlocks and haunches were colored -- dusted a light grey with white appaloosa spots. Her wings were the same snowy color, her pinions a darker gunmetal grey.

“Commander Firefly, I presume.” The mare’s voice was light and airy, with a faint hint of a Prench accent. She extended a hoof to shake. Her sharp blue eyes gave Firefly the uncomfortable feeling of being visually dissected.

“To whom does it concern?” Firefly responded flatly and shook her hoof.

“Special Agent Rafale,” the mare said without missing a beat. “I will skip the pleasantries, commander. I am here on the behalf of Princess Luna and I represent her interests in this operation.”

A shiver went down Firefly’s spine. Despite the fact that the oasis’ climate was far warmer than that of the arctic wastes around it, a palpable chill lingered around Rafale, intensifying when she touched Firefly’s hoof. Was she doing this on purpose? Firefly’s muzzle scrunched up for a moment. Rafale failed to notice, or if she did notice, she failed to emote.

“What interests would the Princess of Equestria hold over a standard antipiracy operation?” Eastwind said.

Rafale turned to Eastwind. Firefly observed similar discomfort from her wingmate as Rafale’s gaze settled upon her. Eastwind, however, was less stoic in her presentation.

“Do you mind?”

“The Princess desires to remain informed of happenings in and around her kingdom.” Rafale said, entirely ignoring her question. “Seeing as the Crystal Empire borders upon Equestria, it is in the Princess’ interest to maintain a watchful eye on operations within this territory.”

“So..." Firefly said. “What exactly needs done, Agent Rafale?”

“While my associates are debriefing our -- shall we say -- guests, I require your assistance to inspect the mineshaft.”

“You’re asking combat fliers to go into a rat hole?” Sunburst was incredulous. “Are you nuts?”

“I am asking my winged combat assets to make the descent first and secure the bottom level for my arcanology team.”

Firefly bristled. “Assets? Excuse you.”

“You are the security team for this installation, no?” Rafale's wording bordered on naive, but the stiffness and seeming lifelessness of her delivery dispelled such impressions handily.

“We were told that we would be relieved when your team arrived,” Firefly growled. “And we are soldiers, not playthings. Unless you have express permission from Commander Brahma Kamal or gods forbid Captain Skywind, we don’t take orders from you!”

“I do not require permission, Commander Firefly,” Rafale replied flatly. Her tone suggested that her statement was a matter of uncontestable fact. Notably absent was any sign of being intimidated by Firefly’s outburst. “My mission comes with full discretionary authority from Princess Luna. I do not usually have to pull rank, but I will not hesitate to do so if it becomes necessary. Will it be necessary, Commander?”

Firefly bruxed her teeth. Rafale was suddenly in charge? Horse shit. Was the CAG informed of this? Was Skywind informed of this? For a moment, Firefly contemplated brandishing her weapon until she got answers. The thought was quickly snuffed as someone else exited the airship.

“Atal?”

The chief arcanist’s long, slender, draconic form was instantly recognizable as he ducked through the open front hatch. The dragon gave a quick glance around, first to Firefly, then to Rafale, then to the Abyss and finally back to Firefly. He raised an eyebrow before uttering with deadpan delivery, “Quite the grave we’ve dug for ourselves, huh, Firefly?”

Firefly breathed a sigh of relief, chuckling inside at the groan-worthy joke. With renewed vigor, Firefly kept her weapon stowed and met eyes with Rafale. “Let me be blunt, Agent Rafale. I don’t trust you, but I do trust Lieutenant al-Adria. Let’s hope you don’t squander his good faith. What is your mission and what do we have to do to accomplish it?”

“Merci, commander.” Rafale continued as though no interruption had taken place. “Prepare your squad and be ready at the edge of the mine shaft in ten minutes. I will brief you on the way in. Au revoir. Lieutenant al-Adria, if you would, please.”

“We will speak later, Firefly,” Atal said with a quick nod before ducking behind the corvette’s forward engine and disappearing into the back hatch. Rafale nodded her goodbye and followed suit, disappearing within the hull of her ship. The squad remained frozen for a moment. Finally, sure that Rafale was out of earshot, Sunburst spoke.

“Celestia's tits,” he cursed. "That was one cold bitch."

“You don’t say no to the Princess," Firefly sighed. "Let's get this over with."

Staggered wingbeats rang hollow in Firefly’s ears. Each flap reverberated in the shaft, slowly tapering off as they were lost in the Abyss below. Firefly could easily stand altitude. No matter how high up she went, she always knew the ground was somewhere beneath. But no one knew how deep the Abyss actually was. Surely it had a bottom; after all, it was bored out by the Keeper’s drilling rig and even a ship that size had limits. Looking down, however, it would be easy to think it bottomless. Firefly reviewed Rafale’s briefing in her head to keep her mind from wandering.

“Timberwolf flight and the griffons of Galatine unit will form the vanguard. You are tasked with scouting the borehole and securing the lowest level of the mine before we deploy Major Valorous Deed’s ground-bound forces. Neutralize any hostile forces you encounter, but do not pursue into the mine until we have established a proper airhead.”

Firefly’s muzzle scrunched at the fluctuations in temperature and humidity as they continued to descend. The first hundred meters were damp but cool, contrasting with the nearly tropical climate on the surface of the Oasis. After that, the temperature began to climb again, and with it the humidity. If she looked closely, Firefly could see wisps of steam sublimating from the soil and rock in the walls of the borehole.

“We will commence exploration of the tunnels after we have fortified the base of our operations.”

The borehole itself was wide enough for the team of eight ponies and griffons to comfortably descend without touching wingtips. They remained in a circle, slowly orbiting the central shaft that ran all the way from the Keeper’s drilling rig to what Firefly presumed was the bottom of the Abyss. The long metal rod was jointed, hinting that it had been assembled in segments, and had teeth cut into its outer surface, which Firefly assumed were used to direct machinery up and down the rod.

Down, down, down the flight team continued. Light from the borehole entrance rapidly dwindled until the other fliers were scarcely shadows floating beside her. All around her, cones of light snapped into existence as the team switched their tactical lights on. The milky circle of her flashlight highlighted layer upon layer of rock and dirt, generously interspersed with tiny glittering violet crystals.

“Crystal density is increasing. We are nearing the vein.”

Were it not for her sudden interjection, Firefly would have forgotten that Rafale had chosen to drop in with them. Despite her cold entrance, Firefly grudgingly gave respect for her willingness get her hooves dirty. Rafale carried the same gear as the other fliers and showed no lack of confidence field-stripping and preparing her repeater prior to their descent. Her callsign -- Maven -- would have been pretentious had she not already shown herself capable.

“How deep do these things usually go?” Thunderlane pondered out loud.

“For an ordinary vein, two or three thousand meters is not uncommon,” Rafale said. “It appears this vein was quite shallow, as we are barely a fraction of that distance below the surface.”

“I wasn’t expecting numbers off the top of your head. You study this in school?”

“I merely read the intel documents I am issued, lieutenant,” Rafale answered flatly. “If it is relevant to the mission, I make it my business to know it.”

“Still don’t get why investigating an abandoned mine requires a REIN operative, an arcanology team, and an armed escort.”

“Like she’s going to tell you, kid,” Sunburst muttered.

“It is a matter of precaution, Lieutenant Thunderlane.”

“Something you’re not telling us, Special Agent?”

“I have told you what is relevant. If additional information becomes relevant, I will be sure to inform you.”

“She’s a regular walking surprise party,” Eastwind chuckled.

Firefly scowled. “I hate surprises.”

“Hey did you see that?” Thunderlane suddenly said.

Firefly adjusted her tactical light, pointing it downward where Thunderlane also had his pointed. In the combined circles of light glinted something metallic. A few more wingbeats and Firefly could pick out a pattern of circular cutouts in a metal surface. They had arrived. The group slowed their descent, circles of illumination sweeping the walls and the surface below as they approached.

“Never thought I’d be so glad to get my hooves back on the ground,” Sunburst said as he touched down.

“Looks like Maresden matting,” Thunderlane mused, tapping on the metal grating with a hoof. “Just like the landing pad on the surface!”

“Guns out, stay sharp!” Firefly barked her orders. “I’m not dying in this hellhole to a damn pirate who thinks he’s being sneaky!”

Every tactical light snapped outward, illuminating the entire inner surface of the borehole walls. The circle of soldiers rotated slowly clockwise, hooves and claws clanking on damp metal, repeaters sweeping the entire borehole until they had completed a full rotation. The final step echoed into the Abyss.

“There’s... nothing here,” Grimmclaw said quizzically, the first words she had uttered since she’d begun the descent.

Firefly quickly looked around. Though there was little more than Maresden matting and the anchor jacks for the utility shaft at the bottom of the borehole, Firefly seethed uncomfortably in her uniform. The borehole smelled of wet earth mixed with the sickly sweetness of machine grease. It was noticeably hotter at the base of the borehole than it was on the surface and an oppressive miasma of humidity smothered the entire area in damp heat and sweat that refused to evaporate.

“Clear,” Firefly said. “Timberwolves, weapons tight. Keep an eye out, but don’t go around shooting up anything that moves.”

“Galatine One and Maven team,” Rafale cut in. “This is Maven Actual. The base of the borehole is secure. You are cleared to descend.”

“Understood, Maven. Galatine, out.”

A metallic groan echoed down the shaft like the wakening throes of some eldritch beast. The faint light of the borehole entrance flickered briefly in sync with a low rumbling that grew in intensity as it approached. Thunderous rumbling sharpened into agitated chattering, agitated chattering into grinding and groaning as the elevator finally rattled to a stop at the base of the shaft.

When she saw it, Firefly was glad she had flown down. “Elevator” was a bit of a misnomer. It was less an elevator and more a metal grate platform with drive motors in the center that engaged the teeth on the utility shaft surface. There were no guard rails, no doors, no covered roof, and no discernable safety features save for a few rings for harnesses on the motor frames.

Like the assault on the Keeper’s bridge, Valor was the first off the elevator, though his demeanor had changed considerably. Valor looked noticeably nonplussed -- even ill -- as he stumbled at last onto solid ground. Firefly caught his eye and raised an eyebrow in wordless inquiry. Valor merely shook his head and waved his commandos off the lift. With the wall of soldiers out of the way, Atal and his team finally stepped off the lift platform, his incorrigible tranquility starkly contrasting with the dis-ease that seemed to permeate the borehole.

“You all right there?” Firefly finally said.

“I don’t want to talk about it,” Valor huffed. He turned to Grimm. “What have we got?”

“The Maresden matting is fresh,” she said, “and there only appears to be one gallery excavated. It looks like they abandoned it shortly after they got started.”

“So the team landed here and then immediately packed up to leave? That doesn’t make any sense,” Valor tapped his chin, then adjusted his light, allowing it to settle on something that glinted faintly.

Firefly followed his light. Her eyes came to rest upon a mass of metal that could easily have been mistaken for a wall. Moving her light over its surface, she found its edges, noting the massive cutouts along its sides. It’s a gear! Indeed, the object was what appeared to be a giant gear, nearly half the diameter of the borehole proper in height. Seams ran along its surface in strange right-angle patterns and a conspicuous bulge in the center of the gear's disc held a drive motor not unlike those which drove the elevator up and down the utility shaft.

“What am I looking at?” Valor's question echoed Firefly's thoughts.

“It’s an Aquellian blast-lock cover,” Grimm replied matter-of-factly.

Valor scratched his head with a hoof. “I’m not exactly an expert on griffon mining techniques, so...”

“My father was an aetherium miner and I used to work on a mining crew before I enlisted.” Firefly suppressed a chuckle. Grimm seemed to thoroughly enjoy dispensing her accrued knowledge. “We used blast-lock covers to seal off unsafe mine areas until they could be reinforced by proper equipment.”

“So there was a collapse here? Some sort of accident?”

“Usually that’s the case. I don't see any evidence of blasting or fire, though.”

"What about magic?" Rafale cut in.

Grimm shrugged. "Raw aetherium does sometimes attract magically-inclined beasts, but if there's ever an accident it usually behaves more like a coal mine explosion than chaos magic gone haywire."

Rafale's eyes narrowed. “Lieutenant al-Adria, I want to know what’s behind that door.”

The sorcerer-dragon’s eyes glowed briefly as he peered into the aether. “There are faint magical signatures that I cannot identify without the proper scrying procedures. They appear to be dispersed across a wide area beyond the door."

“What if it’s just interference?” Eastwind said. “We are in the middle of an aetherium vein in a geologically active site.”

Rafale did not appear convinced. “We’re going in.”

“Uh, not to rain on your picnic, but there's probably a good reason they sealed that entrance.”

“Your objection has been noted, lieutenant Thunderlane. I shall include it in my report. Open the door, Major.”

Everyone looked to Valor. The Major was clearly conflicted; Firefly could see it in his eyes. Surely ever combat instinct told him to leave sealed doors lie, but orders were still orders. After an uncomfortable pause, Valor finally looked to his demolition griffon and grudgingly nodded. “Can you get this open, Grimm?”

“I think so,” she said, walking over to the control panel. “It’s a fail-secure lock. I’ll need to run a bypass on the lock wiring or it will weld itself shut with thermite.”

“What’s keeping us from blowing the door down with demo charges or a ballistic lance?” Sunburst asked.

“This is a geothermal oasis.” Grimm huffed as if Sunburst had just asked the stupidest possible question in the world. “You set off uncontrolled explosives in an unreinforced passage and you could bring the whole damn mine down. Trust me, you don’t want to blow that door.”

“She’s the expert, abuelo,” Thunderlane whispered out of the corner of his mouth to Sunburst. The older stallion gritted his teeth and mumbled some unintelligible curse under his breath. As Grimm went to work, Thunderlane turned to Firefly. “What do you think is on the other side, jefa?”

Firefly’s eyes remained fixed upon the door. She had no idea what to expect on the other side. Quarry eel? Hydra? Manticore? Hopefully a simple aetherium mine and nothing more? “I have no idea, kid. But whatever it is can’t be good.”

“Aha!” Grimm squawked happily. “Easy peasy. That was a piss-poor lockup if I’ve ever seen one!”

“Galatine,” Valor barked his orders, “I want all guns pointed down that passage. Grimm, open the door.”

“Yes, sir.”

Grimm threw the switch closed in a shower of electric purple sparks. A high-pitched whine filled Firefly’s ears as the circuit’s closure energized the motor, followed by a terrific groaning as the door’s mechanism ground to life. The outer ring of gear teeth lurched forward, its clattering advance along the toothed rack echoing violently through the borehole. Finally, the blast cover clanged against the rack stops, grinding to a halt.

Flashlight beams pierced the darkness ahead, revealing a gallery as large in diameter as the blast cover itself. The walls of the gallery appeared to be carved from a single massive crystal of amethyst. Marbling of all shades of violet streamed through the mineralized walls, shimmering in the artificial illumination cast by the troop’s flashlights. Small pinpoints of crystalline iridescence glinted through the translucent aetherium walls.

“This is making less sense as we go along,” Grimm mused. “The vein is perfect and they barely touched it.”

Hoof falls rang hollow as they continued deeper into the gallery. All this time Rafale had remained silent. Firefly continued to steal glances at her as they trotted along, but the mare was damnably difficult to read. In spite of the heat, the humidity, and the oppressive claustrophobia of being below ground, Rafale had maintained the same stony-faced, ice-cold disposition that she had established on the landing pad.

Suddenly, Thunderlane stopped and sniffed at the air. “What’s that smell?”

Firefly took a quick wiff of it herself. An bitter chemical odor lingered in the air that stung the nostrils and evoked the atmosphere of working on an airship drydock or repair shop; or the Majestic’s main hangar immediately after combat action. Firefly quickly held up her hoof in the “stop” motion.

“It’s half burned LACE fuel. Everypony stop! Masks on!”

Part of their descent gear included respirators in the event that they entered gas pockets or other hazardous areas. There was a mass shuffle of uniforms, hooves, claws, and canvas as ponies and griffons donned their respirators. Firefly could hear grumbling throughout. It appeared that she wasn’t the only one to resent respirators.

“I hate this shit,” Sunburst mumbled through his mask. “It’s like trying to breathe through a soda straw while looking through it at the same time.”

“Forget to take your breathing meds this morning, old sire?” Eastwind cracked.

“Hey now!” Sunburst very nearly burst out laughing at his own retort. “Just because you’re good at sucking tiny things doesn’t mean the rest of us are!”

A collective “ooohhhhh” went up throughout the troop before dissolving into smatterings of laughter. Firefly cracked a smile and shook her head. The sheer look of shock that crossed Eastwind’s face was priceless. It only took a moment, however, before she was laughing as well.

“I’ll admit,” she said through a fit of giggles, “I didn’t expect a comeback.”

“Opportunity knocked,” Sunburst said smugly, “and I answered!”

“There is something at the end of the tunnel.” Rafale’s monotone pronouncement silenced the entire troop.

All tactical lights focused on what Rafale had fixed her flashlight upon. Firefly squinted into the harsh light, gradually resolving the strange shape to be a boxy, open-topped machine with a massive drilling apparatus at its nose. Even through the filtered air of the respirator, she could sense a sharpness to the smell of engine exhaust. If it was even creeping through the filters, it would surely have been lethal to exposed lungs.

“Luna’s ass,” Sunburst spat, “I can smell the exhaust through my mask! It’s really thick back here. They must have left this thing running when they bailed.”

“Sweep this area,” Rafale ordered. “Galatine and Timberwolf, check the machine for any stowaways. Maven team, I want a full intelligence workup.”

With the chorus of affirmatives from all teams, Firefly gingerly trotted forward. The tracks on the gallery floor were multifarious, being composed of both hooves and talons. The mining crew was multi-racial. Closer inspection of the drilling rig confirmed it, as shed feathers and unattended saddlebags rested in tool cubbies on the machine’s chassis. Perhaps there was a fight? Or an accident?

There was no sign of struggle, however. No blood, no shell casings, no weapons, and certainly no dead bodies. Despite the lack of obvious threat, Firefly’s danger sense and curiosity were both piqued. Something was not right here.

“Shit!”

Eastwind’s exclamation immediately drew Firefly’s attention. “What is it?”

It took Eastwind a moment to collect herself and when she did, her voice was uncharacteristically shaky. “Look..."

Firefly followed Eastwind’s hoof with her own flashlight beam. Atop the drilling rig directly in front of the control cabin two crystalline orbs glinted in the dim light. As the beam settled on them, Firefly puzzled over what had caused her wingmate’s fright. Cold claws of dread gripped her gut as realization dawned upon her.

THE EYES. THE EYES. THE CRYSTAL EYES.

The words that the crew screamed echoed in her head. Firefly inched closer. In the cold circle of white, she saw it. Orbs became eyes. Eyes were set deep in an ashen white skull. Skull and jaw were locked in rigor mortis, suspended in violet crystal. Suddenly, from above, a tiny pebble of purple glass clattered onto the metal of the control cab, coming to rest next to the pony skull. Firefly looked straight up, tracing its path up to the ceiling of the gallery.

“Oh my gods,” she whispered, her eyes locked upon the sight.

A constellation of crystalline orbs gleamed in the flashlight beam. Firefly traced her light along the ceiling, revealing only more orbs. They were countless, stretching along every surface in the gallery. Everywhere she looked orbs upon orbs upon orbs shone in the darkness.

Each pair of orbs became eyes. Each pair of eyes were set deep in an ashen white skull. Skulls and jaws were locked in rigor mortis, suspended by an ocean of transparent purple glass. Firefly’s eyes widened in shock. Gasps and cries of surprise and fright rose all around her as each sweep of a flashlight beam uncovered horror upon horror.

“This isn't a mine, this is a mass grave!”

Author's Notes:

Just in time for Halloween.