“This doesn’t look like the toughest vault in Equestria,” Twilight muttered, squinting through the gloom at the donut shop. It was closed, like so many other things this late at night. Nopony wanted a donut at midnight. I know this place. Donut Joe, are you a vampire too?
She doubted it, but Twilight made a mental note to check, just in case.
“That’s because you don’t know what you’re looking for,” Rarity said, turning sharply as they passed the alley. Twilight was forced to follow along behind—though there wasn’t another soul on the street with them. There was no chance they weren’t being watched, if this really was a place worth protecting.
“If it looked like a fortress, ponies would want to come and rob it. That’s the nature of the beast. Building an unbreakable lock is just an invitation for the best lockpicks to try their hoof until they get inside.”
She stopped in front of the back door, lowering her colored lenses. Twilight’s horn started to glow with a simple unlocking spell—and Rarity stuck out a hoof. “Stop! Dear, are you trying to get us killed?”
Twilight did stop, though she felt only confusion. “Rarity, uh… what are you talking about?”
Her friend lifted the glasses, settling them on the bridge of Twilight’s nose. Patterns appeared on the wood, written in the faint lines of runes, surging with power. It was unicorn magic, but the hoof that had written it had done so with such masterful skill that Twilight had to squint to even read what they’d written.
“Sweet Celestia, that’s… incredible.”
“Incredibly dangerous, certainly. I happen to know what this charm does. Suffice it to say we would not survive the encounter if you forced the door.”
Rarity lifted the glasses back off Twilight’s face, then reached into her case from before. Despite her violent opening earlier, it had taken only a modest beating. The locks still worked, and her tools were still safe inside.
Rarity lifted a length of rusty chain from inside, except—the links weren’t made of any metal Twilight recognized. Was she losing her mind, or were they flowing, like each one was made of invisible glass and liquid lead was inside.
Rarity lifted the chain in her magic, holding it up to the door. Then she whispered a spell, the one-word counterspell taught to foals in magical kindergarten.
The chain melted, spreading out around the door like a living thing. It covered every surface, concealed every bit of the places Twilight knew the runes were written, until the door seemed to be made of dull metal and not sturdy wood.
“What was—”
“Stygian lead,” Rarity whispered. “And if you’re about to ask where I got such a priceless object and how I even found any, now you know the perks of selling to the elite of Equestria.”
She reached out, twisting the knob and swinging the door open. “When you create priceless work, it demands something of equal worth in exchange.”
The door slid open, revealing—the back of a donut shop. Sacks of flour and sugar, an oversized mixing machine, an industrial icebox with liquid dripping out from the grate at the bottom into a drain.
Rarity seemed to know where she was going—though perhaps she was just following what her glasses let her see and Twilight could not. She marched straight over to the icebox, then lifted the grate with her magic and looked down. There was a black shaft, seeming to vanish into the bowels of Canterlot. Twilight lit up her horn for a second, but she still couldn’t see the bottom.
Rarity didn’t even hesitate. In one hoof she lifted a tight coil of thin metal wire from her case, so thin Twilight couldn’t imagine it supporting her weight. Then came the harness. She slipped it on with incredible speed, without so much as ruffling the armor she was wearing. “I’m afraid I didn’t pack for two, dear. You’ll have to… well, I trust you know some kind of spell for long drops.”
Twilight rolled her eyes, then pulled the dress gently down from her shoulders. She removed it as delicately as she could, but she could hear Rarity wince as the fabric strained, so obviously she hadn’t done a terribly good job. “I’ve got wings now.”
“Right.” Rarity looked at them, frowning to herself. “If any of our targets see that, Luna will kill me. She’ll probably kill me anyway when we finish, so I suppose I can’t be deader. You, though… may want to find something to do about them. You’re a princess now—do you really want the Crown to be implicated directly?”
Twilight winced, hanging up the dress on the edge of the mixer. From Rarity’s expression, that was not where she thought it belonged. “You just got through explaining how evil they were, and how much better it would be to break a little law to stop them from breaking the important ones—now suddenly it matters?”
“It always mattered. I just didn’t think you would actually go through with it until now.” Rarity tied off the cable around the edge of the icebox, then walked backwards until she was hanging off the edge, swallowed by blackness. “We have less than an hour before the next round of guards patrol this direction. No time to talk.” And she was gone, vanishing into the gloom.
Twilight watched, counting off the seconds and considering a flight out into the night. She could abandon this insane mission now…
And leave Rarity to her fate. And Sweetie Belle, and anypony else who had become a vampire against their will. We’ll be doing something good tonight.
She jumped, spreading her wings in a glide. The space was tight, barely enough for her whole wingspan. But gliding was the first thing she’d learned, and she did it well enough. Rarity’s form appeared below her, and there was the cable hanging vertically on the edge of the shaft. She flapped a little, slowing her fall enough that she wouldn’t hit her friend.
They passed quickly through what should’ve been a sewage drain, which had been cut and sliced through and a clear shaft down opened. A shaft that led them swiftly into the Canterlot Caverns. Twilight’s horn lit up, sending fractals of greens and blues and pinks shining through crystal formations as large as her library back home.
At least the cave was wider than the shaft, giving Twilight a little more room to maneuver. As a result, by the time she touched down, it was in slow, controlled circles, just like Rainbow Dash had taught her.
Rarity slipped out of the harness, leaving it hanging a foot above the ground by the thin cable.
“I didn’t know you had so much experience with climbing.”
Rarity chuckled. “Less than I’d like to. But here we are—the first difficulty has been overcome. A greater one remains before us, however.” She gestured, and Twilight saw the vault door.
This was what she’d been expecting, though now that it was before her, she found her imagination had failed to do it justice.
It was made of metal so dark it was black, nearly three stories tall and covered with interlocking wheels, gears, and mechanisms. This was no creation of a modern tinkerer—an ancient master of the craft had built this, from materials so perfect that she couldn’t have slipped a knife between the gears.
The door was set into a single, flawless white crystal that towered over their heads, breaking twilight’s lavender glow into a thousand shades. Stars and stones, that’s a diamond.
“They really didn’t want anypony getting in,” Twilight said, her voice weak. “No guards down here, so that’s good. I guess they must not come here often.”
“Nope,” Rarity agreed. “This is where Regolith keeps his oldest, most valuable objects.”
“R-Regolith?” Twilight repeated. “As in… Nightmare Moon’s vizier? He’s… a-alive?”
“You say alive,” Rarity said, her voice scornful. “We’ll say he’s still active and that’s certainly true. Alive… not so much. Regolith was already old in those days. Stories don’t quite agree whether he studied under Starswirl or taught him, and he isn’t telling. One thing we do know—Nightmare Moon’s other closest generals and servants died in the rebellion or were killed afterwards. It was thought that the curse she brought to the world had been destroyed as well. But… Regolith was clever, and subtle, and he never put himself in danger.”
Twilight began to walk slowly around the front of the vault, lighting up her horn a little brighter. Her first instinct whenever she saw a locked door was just to teleport around it—but something told her a two-thousand-year-old master sorcerer had considered that option. If one in every three ponies might just get in whenever they want, it wouldn’t be a very good safe.
“So he survived, shared his gift with ponies who had something to offer him. Then they shared it with ponies under them, and… well, eventually my sister.”
Twilight nodded gravely, not taking her eyes from the door. As fascinating as the ancient mysteries of Equestria’s past were, she now had something even more interesting. A puzzle.
“You planned on getting into this thing…” she said. “I’m assuming you knew how. Did you steal the key?”
“No key,” Rarity answered. “See, no keyhole. It’s a puzzle lock of some kind. I have it on witness account that Regolith himself is the only pony who ever opens it. He often travels here without clothing or supplies, yet he enters the vault. The key must be something more esoteric.” She sat back on her haunches, removing a sheet of paper from her bag. Twilight glanced and saw it was an image of this very door, though grainy and looking like it was really the photo of a photo of a photo several layers deep.
“Perhaps your presence here can be of assistance,” Rarity went on, almost casually. “You’re one of the cleverest ponies I know, Twilight. Fresh eyes and all that.”
Twilight walked over, levitating the photo and holding it up so she could look between it and the door and back again. Rarity had scribbled notes in the margins describing her ideas about how to open it, but Twilight ignored them completely.
This might be the lock of an ancient vampire built deep into the mountains, but a puzzle was a puzzle.
After a few minutes, she sat up, pointing suddenly. “It’s these wheels, here. These four. The carvings worked into them represent the seasons. But the areas around each… that’s a lily next to the winter gear, that doesn’t make sense.” She pushed gently with her magic, and found the gear gave easily under her pressure, like it had been well greased and prepared to move. When it reached the barren tree without any leaves, it sunk in an inch or so with a satisfying click.
“Be careful, dear.” While Twilight had been working, Rarity had drawn and armed her crossbow again, and now held it at the ready, looking out into the gloom around the vault door. So far as Twilight could see, there was nothing out there—nothing yet. “This lock is so heavily enchanted that I can’t make sense of the spells. It’s old and powerful and probably not made by a pony who was terribly concerned with what happened to thieves.”
Twilight nodded, settling the other three locks into place in order. After winter came spring, then summer, and finally fall. Each rotated around until it sunk down an inch or so—and the mechanism expanded like a flower. Behind thin metal sheets were more dials and levers.
She probably wouldn’t have been able to open it, except for the notes Rarity had scribbled onto her photograph. They weren’t actually Rarity’s speculations—they were clues she’d gathered.
Twilight skimmed them quickly, glancing back and forth between the real object and the image. The lock had been assembled by a master clockmaker in the third century, and apparently he had belonged to a particular religious sect. He hadn’t used an arbitrary combination, but had chosen each aspect of the lock with purpose. This door wasn’t meant for storing valuables, opening it was supposed to be a religious experience, a ritual.
Twilight had studied the Foundationalists. With each step further she got in the process, she grew more confident.
“I can’t believe it,” Rarity whispered. “I was half expecting we would have to break it down. I’m told a single mistake will reset the entire lock.”
Twilight was chewing on a quill. She wasn’t even sure where it had come from. “It would,” she said, rotating her hoof slightly to the rest on the section of the latest part of the lock—which corresponded to the progression of the equinoxes and the movement of constellations through the sky. “And it’s timed, don’t interrupt me.”
“Forgive me.” Rarity sat back. “You’re clearly enjoying this. I’ll leave you to work.”
Twilight barely even felt time passing. Each movement of her hooves, each twist of a dial or a lever felt like the clockmaker was talking to her, out of the ancient recesses of time. Whether it took hours or only seconds, she couldn’t have said.
But then she finished. There was a reverberating click, and a series of chimes that shook the entire crystal like a gong.
“Damn,” Rarity swore, backing up from where she had been watching the ceiling. “That… wasn’t exactly a subtle failure, was it—”
“Not a failure.” The door didn’t swing open so much as it lensed open like an iris right in the center, just barely wide enough for an alicorn to squeeze through. Rarity wouldn’t have as much of a problem, though she would have to climb up to it somehow.
“Oh.” Rarity’s expression relaxed. “In that case I only wish it could publish our success a little less widely. I’m guessing ponies will be listening for that.”
Twilight could hear something—from out in the caverns all around them. Their cave was a massive room, cleared of even fallen rocks and debris—but there were many openings, cracks in the crystal walls into other caverns. And from those openings, she could hear ponies moving. Voices maybe, or a growling that was like voices.
“We should move,” Rarity said. They did. Twilight winced as she went through the opening, twisting her head so that her horn wouldn’t scrape along the ceiling. She sucked in as much as she could, then struggled through the gap.
There was no drop on the other side—she slid along a crystal floor lit by the diffuse light streaming in from all sides.
Here was the treasure room she’d imagined—there were fewer objects than she’d expected, perhaps half a dozen in all. Each one had its own velvet pedestal—an intricate metal puzzle box, a strange flat object with black material on one side and perfect glass on the other. An old cup.
The space itself wasn’t large—there was barely enough room in the crystal for her to crawl, and even Rarity had to move cautiously. The diamond all around them made it clear they would not be cutting their way out, and didn’t look like it would so much as budge from Twilight’s most powerful spells.
They rounded a corner, and Rarity stopped dead, gasping.
“What a predictable pleasure to see you here this evening, Lady Rarity,” said a voice. It wasn’t one Twilight had ever heard before—male, deep and resonant, yet strangely flavored with complex shades of emotion that made it difficult to classify. It wasn’t quite anger, or amusement, or even frustration.
Rarity made room for her, and Twilight saw no reason to turn around.
Through a little doorway was something like a magical researcher’s laboratory, with every tool and every object a perfectly worked artistic masterpiece. An alembic resting over a heating crystal had flames carved into the side so realistic that Twilight could almost see them sparkle. Even the table was encrusted with gems, and the titles visible poking out of the bookshelf would each have fetched the price of a house in Canterlot’s downtown with bits to spare for a carriage to go with it.
“Regolith,” Twilight said.