“Doug!” Cadance shouts as the human falls from view.

A pink blur moves in an instant. The floor under Doug’s feet had split in two, dumping him down a chasm wide enough to keep a pony from touching either side but too narrow for wings to be practical. Her feathers stay tucked to her sides as she dives, clattering loudly as she bashes against the wall, her purple and pink and gold tail last to disappear.

“Cadance!” Twilight and Rarity scream as they rush forward, cursing at their delay, only for the trapdoor to swing shut with a booming thud. Rarity skids to a stop at the edge while Twilight leaps upward, wings flaring as she slams into the floor. But it holds fast, made to support Celestia’s weight when not triggered, leaving her hooves smarting from the impact.

“The latch!” Rarity calls, fumbling around until she finds the spot where Twilight’s rump landed. The trap clicks open once again; Twilight stands on the edge and stares down until Rarity joins her, having placed a rock on the trigger to keep it open.

The shaft through which Cadance dove extends down, down, down, smooth metal on the sides receding into inky darkness and nary a torch to light the way. No light comes from the bottom, no trace of the fallen human or the alicorn who dove after him.

While pegasi prefer their open spaces and lofty, towering halls, up is not the only direction ponies build. Earth ponies, and to an extent unicorns, dig down into their namesake, delving deep for ores and veins of precious metals while their horned brethren search for caverns of crystal and gems. One needs only look at Mount Canterhorn, the hollowed husk of a mountain stripped bare of resources and converted to apartments, grand villas, and a majestic shining castle. Alicorns, thus, prefer the style of all three breeds, and the Castle of the Two Sisters is a perfect - though dilapidated and half-demolished - example.

“T-they’re okay,” Twilight reassures the ashen-faced unicorn, for all the good it does. “Celestia and Luna wouldn’t have sent ponies plummeting to their death, there would have been a spell on the bottom to cushion their fall.”

“Magic doesn’t always work on Doug,” Rarity whispers, sounding dead. And no wonder; when she and Rainbow Dash competed at the Best Young Fliers competition the cloudwalking spell Twilight cast on all of them failed due to Doug’s null nature, leaving the glamorous dancer plummeting and saved through her herdmate’s quick action.

Twilight gulps, her heart skipping a beat. “Cadance will have grabbed him,” she claims, the words flat even to her ears. The former pegasus, much like Rainbow Dash, must have had ‘Pony Overboard!’ drilled into her from a young age to have such a decisive and quick reaction. She berates herself for never developing the same instincts, but now is not the time for recriminations. “And we can’t go after them, not directly.” Not that Rarity had moved to do so. “If this was a trap, the place it took them to is likely trapped as well.” Could Cadance teleport? Possibly not, depending on what’s around her, and she’s not sure if all of Doug would come along for the ride, the main reason nopony has tried with him. “Come on, let’s find where they fell.”

Half a dozen options present themselves, hallways off the main corridor that lead to more and more tall doors. She opens one experimentally, only to find a bleak and bare room covered in dust. She shuts the door with a heavy sigh and glances at the unicorn still standing by the open trapdoor. “Alright, no need to panic. This will go faster if we split up. We just need to find a way down, and… Um, Rarity, what are you doing?”

Twilight takes a step back at Rarity’s stern approach and winces as the hoof gently clocks her in the head.

“Haven’t you played Ogres and Oubliettes?” Rarity admonishes, masking her scowl with a thin smile. “Never split the party. What would happen if we found another of those traps? A rotating door, or a tunnel that spits us outside?”

“Okay, you have a point,” Twilight admits, rubbing the sore spot on her head. “You take the left doors, I’ll take the right.”

“Better.” Rarity huffs as she opens one door, just as quickly closing it. “What makes you think that we can find anything down these dusty passages? Now, maybe if we had a map or…”

Twilight turns around to see what caused Rarity to trail off, her eyes slowly widening. Outside, all that decorate the once majestic halls are scraps of fabric, bits of blue trimmed in silver or gold embossed in alabaster, and bars to hold banners that instead hold empty rods or nothing, leaving bare stone to greet any visitors. Yet inside this room? Rarity already has one of the spare banners unfurled, a magnificent design of stars in glimmering silver on a night sky of cobalt that would stretch from floor to vaulted ceilings. Rolled bundles form neat stacks, each the size of a pony, half in Celestial orange and the other in Lunar blue.

“You go on ahead,” Rarity absentmindedly shoos, flicking a hoof in Twilight’s vague direction, her eyes transfixed on the banners. “I’ll stay here, and, um, wait for them.”

“What happened to ‘never split the party’?” Twilight rolls her eyes as Rarity makes no move to follow her out. “Those sat there for a thousand years. They can wait a few more minutes.”

“But, but, but,” Rarity objects, then lets out a single exasperated huff at Twilight’s insistent gaze. “Oh, fine. But if any moths decide to make these hangings their homes, I shall be very cross with you. Not only I, but all of Equestria! For theirs will be the true loss of such finery!”

“Ah huh. Come on, the sooner we find them, the sooner you can get back here.” Twilight steps out, then waits. And waits. Her eyes go to the ceiling before she spins around. “Rarity!”

The unicorn has two bolts tilted up, one gold and one blue, inspecting the bottom for any imperfections. “Oh, Twilight,” she begs, “surely it wouldn’t be improper to take one of these along? For inspiration?”

“One,” Twilight allows.

“Oh…” Rarity gnaws at her lip, frantically glancing between the rolled up banners. “Oh, I cannot! Surely you wouldn’t force a dam to choose between two of her foals!”

“You only have one foal,” Twilight deadpans.

“Right now,” Rarity counters, flustered. “I’ll have my second soon enough.” She grunts as she hoists the bolts up, barely able to manage one at a time, and lays them across her back. It’s a good thing the doors are so wide, or it might have been tough to fit. “Ooh! Well, it’s like Applejack says, a little hard work is good for the body, yes?” She strains to grin at Twilight. “Now, where are we going?”

“This way.” Twilight continues down the hallway, trying doors on left and right but finding nothing but empty and dusty rooms. She comes to the end of the hallway, a T intersection with a door opposite her. She glances left, then right, and tries the door.

A few short tables lay in the center of the large room, piled high with books. Shelves line the walls, crammed with books of every shape and size. One shelf has been pulled away from the wall, the secret entrance she came through a few months ago, the inside of that chamber empty and dark.

“Booooks,” Twilight draws out, a dribble of drool dripping out her gaping muzzle. Doug is probably fine, he has Cadance to look after him, right? No worries. She can take her time, she doesn’t have anything pressing to get to. They can wait wherever they are while she looks through these books. One day won’t hurt them! Or two. They’d be fine after two.

Rarity shoulders past her, dropping the banners next to the table and plopping down with a giddy grin.

“No!” Twilight shakes her head in a vain attempt to dislodge the siren call. “No, we have to keep looking! We need to…”

“Find a map?” Rarity has found a blank sheet of paper and a pencil and busily sketches designs similar to the solar skyscapes and lunar landscapes depicted on the banners, completely engrossed in her work.

“...Yes. A map.” Twilight plops down next to Rarity. The books on the table are all the ones she sorted through when Discord betrayed them, all titles from far in the past that might have helped with Lord Tirek. None seem particularly relevant, although they could use a second look…

“Oh!” Twilight exclaims after a time, having skimmed through half the selections, grinning as she pulls out a purple book embossed in gold with two orange and yellow alicorns crossing their horns and grinning upward. On the bottom half six gems depict the Elements of Harmony in their pentagonal configuration with purple in the middle, all inside a golden crown decked with diamonds. “This is Celestia and Luna’s journal! The Journal of the Two Sisters!”

“Mm,” Rarity replies absentmindedly, having filled two pages with drawings. She glances over, eyes lighting up at seeing the artwork, and reads over Twilight’s shoulder.

A pang of doubt fills Twilight at rifling through what might be the Princesses’ secret thoughts. But, it’s a book; they wouldn’t have written anything down they didn’t want to potentially get out. And they wrote it together. And they are all herdmates now; herdmates shouldn’t have secrets from each other! Right? Right.

She cracks the book open, both of them giggling at the little pink stars and golden hearts and orange suns dotting the borders. Rarity’s breath catches at a doodle of her cutie mark, but it’s the same as the Element of Harmony. Half of the book is a golden yellow done in Celestia’s elegant hoofscript, the other half a dark blue cursive quilled by Luna. Twilight fondly strokes the gold and brown sketch of Star Swirl the Bearded, huffing as Rarity flips ahead to the crude representations of alicorns.

Some time later, the sun having long gone down, a low booming echoes from every wall.

“That…” Rarity stammers, going from yawning to alert in an instant. “What was that?”

“That sound…” Twilight flips back a few pages, hornlight glowing brighter to better illuminate the pages. “That could be the Organ to the Outside!”

The tone changes, a different note played a few times. It doesn’t sound like a message in Mare’s Code, but Twilight jots the number and length down anyway.

“Yes! It could be! And recall-” Rarity flips back a few more “-that Princess Luna wished a trapdoor to be built into her very throne! And look at this. It’s a schematic for the Organ, and one of these triggers leads to a trapdoor, another one the throne!”

“Yes, but that escape route takes you outside.” Twilight frowns. “Which, actually, sounds like a security hazard. If somepony found that way in, they could be underneath you without any sort of warning.”

“Luna could have trapped the entrance,” Rarity suggests, “much like she trapped the rest of this castle. Honestly, portraits one can spy through? Revolving doors? Trick levers built into walls? Those seem more suited to scaring ponies passing through than any sort of defense against a determined attacker.”

“They were that confident in their abilities?” Twilight shrugs. “But, how would you use the Organ to escape if you had to be sitting on the throne at the same time?”

“Not,” Rarity says with a smirk, “if it’s for an impudent sister sitting on her throne. Or one of those early royalty they entertained. If any of them were as rude as they claim Princess Platinum was? I’m not saying I know somepony who could use a quick chute to the outside, but…”

Twilight snorts. “Okay, you have a fair point. And if Luna wanted to play this prank, she would need a fast way to get there. This trapdoor here? If we follow the diagram, it should be located…”

Twilight glances around, measuring the ceiling and walls, then takes off the way they came with Rarity hot on her hooves. They quickly come to an ornate room with two large banners over two thrones, a large hole in the center of the wall between two tall banners, the same as Rarity had on her back.

“Here.” Twilight points to a side alcove just out of view of the thrones.

“There you are!”

The two glance up to see the large hole shrink by about a pony’s size. Light from the moon reflects off the prismatic mane, Rainbow Dash a mottled gray as she descends.

“Took you two long enough. You weren’t off…” Rainbow Dash trails off as she spots the book in Twilight’s raspberry aura, her smirk disappearing. “Oh. You found books.”

“We found a map of the castle in the library,” Twilight retorts defensively.

“Yeah, well, at least you weren’t roaming around the grounds.” Rainbow Dash sticks out her tongue. “We’d spot Doug or Cadance on one side of the castle, wandering around like they’re lost, then by the time we alerted each other they’d be gone or on the other side. This place has more holes than Fluttershy’s.”

“Do you know where they are now?” Twilight asks, glancing down. Hopefully they haven’t wandered off again, the organ has been quiet for a while now.

“Yeah, Misty’s keeping an eye on them.” Rainbow Dash frowns as she zips back up to the hole, glancing back at the land-bound unicorn. “Can you teleport Rarity there? They didn’t exactly make this the easiest castle to navigate if you can’t fly.”

“Don’t worry about me,” Rarity says, giving Twilight a quick nod. “There’s a certain room calling my name, and I would hate for you to have to lug all those heavy banners around. That’s what Doug’s for.”

Twilight and Rainbow Dash snort. “Let’s go find that porter of yours, then.” They take to the air, leaving Rarity to study the twin thrones, and zip down to another opening.

This room is nearly as large as the throne room, dominated by a massive organ. Thick pipes extend upward and out, only half opening while the others disappear into walls, presumably to pipe the music to every corner of the castle. Doug sits at the keyboard, one hand on the keys, Cadance’s chest pressing against his back, her attention on his fingers.

“Stretch a little further,” Cadance commands while she shows which keys his fingers should be on. “Good. Now, how do you think it goes again?”

He pounds out a simple, yet dark and foreboding tune.

~Daahn Daahn Daahn Dun Dah Daahn Dun Dah Daaahn, Daah Daah Daah Dah Da Daahn Dun Dah Daahn~

Twilight frowns. “Where did you learn The Storm King’s March?”

“Is that what it’s called here?” Doug glances over, flexing his hand. Two leg-shaped bruises stand dark against the Celestia crest. “I heard it in a movie. It’s a tossup which sounds better, a full orchestra or an organ this grand.” He gladly accepts Twilight and Rarity to his side. “I can’t quite reach the right notes, your keys are too big. Not that I can really play.”

“I thought it sounded great.” Cadance winks, then gently pushes Doug to the side. Her horn lights, half a dozen keys depressing at a time and continuing the melody from where Doug left off.

The discordant music sends chills down Twilight’s spine; she feels like any moment a hundred armored Storm Troops will come marching through the door, the Storm King in the lead.

“I think I’ve made my decision,” Cadance says as she lets up on the keys, a huge grin at Twilight. “But first?”

Twilight grins back as Doug tries to improvise on the organ. ~”Sunshine, sunshine, ladybugs awake! Clap your hooves and do a little shake!”~

“I’d love to stay here,” Cadance says, attempting to nuzzle Twilight into submission.

“That’s great!” Twilight pulls out the journal despite being under assault. “I found a map that includes all the secret-”

“Nope!” Cadance pushes the journal back to Twilight. “I’d much rather find all the secret entrances and passageways myself. Far more fun that way!”

“Fun,” Doug spits out, rubbing at his chest.

“Hey, I caught you,” Cadance retorts, though she leans down to gently nuzzle the higher of the two bruises. It makes Twilight a bit jealous (and perhaps worried) to see the married mare treating her stallion so intimately, though Doug seems more perturbed than passionate.

Doug takes a deep breath, then lets it and his anger out. “That you did,” he says cheerfully, giving Cadance one of his cherished ear rubs.

She nickers as she lowers her head to the other bruise, and Twilight has the brief fear that she is going to keep going down.

Doug seems to have the same thought, propping her up and twisting so Cadance is again focusing on Twilight. “Now, didn’t you have something to say?”

“It’s getting late,” Cadance remarks, glancing at the starry sky outside. “Or, it is already. Did you want to bed down here, or-”

“Nope!” Rainbow Dash cuts in, forcing herself in between Cadance and Doug and staring up at the human with eager eyes, not at all hiding the possessiveness Twilight is feeling. “Come on, big guy. They’ve all given you rides. Now it’s my turn!”

“Dash,” Doug starts, though his objection falters when he sees the resolve in her eyes.

He offers her a hopeful smile as she leads him away from the organ, and reluctantly mounts between her neck and wings, just above her withers. It makes a comical sight, like Trixie hornlessly ‘levitating’ an unbalanced board: his feet touch the ground even when on her back, and if he leans forward he’d look straight into her eyes. It might make sense for him to put his legs behind her wings and lay across her, but then she’s certain they’d at least attempt ‘no wings’ on the way back.

“You good?” Doug asks.

“Careful,” Twilight warns before the pegasus can take off. She earns herself an eye roll, but at least Rainbow waits to hear what she has to say. “You can’t use your magic to accelerate him like you would yourself. You might leave him in the dust, or worse, falling. You’ve got to do it entirely by force. He’s got a strong grip, but it’s not unbreakable.”

“Don’t worry about a thing! We’ll be back home in ten seconds flat!” Rainbow Dash snorts as she takes to the air. At first she struggles with the imbalance, a bit stricken at the implications of her proposed maneuver. “Right. T-thanks. I’ll keep it slow.” She glances back at Doug. “Do you trust me?”

“With my life.” He hugs her tighter.

“Dude, careful; I don’t have a neck like Twi over there.” Rainbow Dash winks at him nonetheless, slowly gaining altitude. Suddenly, her face lights up. “Omygosh omygosh omygosh! We could go to my place! I’ll ask Flutters if she wants to swap!”

“Err,” Doug says, glancing back at Twilight only for the two to disappear outside.

Next Chapter: Ch. 142 - Careful Planning, Part One Estimated time remaining: 9 Hours, 31 Minutes