Rainbow Dash streaked down through the narrow, pitch black well, following the sound of Derring-Do's terrified screams. She could fly much faster than most ponies could fall, but here she had absolutely no room to maneuver. Her eyes still hadn't adjusted to the darkness, either: her glow stick necklace cast a faint green light on the walls, but only reached a couple yards ahead of her.
At first, Derring-Do's screams were distant and warped... but soon the distortion vanished entirely, and Dash slammed into her from above. Derring scrambled like mad to grab hold of her, sending Dash off balance and scraping her wingtips against the stone walls. As soon as they locked their hooves together Dash snapped her wings out. She pushed against the wind, desperate to break their fall, but Derring-Do pulled her down like an anchor. Twice Dash spread her wings too far and bounced off the wall, spinning wildly out of control.
The claustrophobic well vanished around them as they fell down through the ceiling of a huge, circular hall. Rainbow Dash spread her wings wide and caught the air for three precious seconds, clinging to Derring's legs as hard as she could. They landed on the top of a rectangular stone slab and tumbled down a small pyramid in the floor, finally coming to rest in a tangled heap. A nearby torch lying on the ground—the same torch the cult leader had dropped—cast a flickering yellow light across the room, and filled the air with greasy, oily smoke. They spent several seconds staring at the domed ceiling and gasping for breath.
"You okay?" said Dash.
Derring gritted her teeth and sat upright. "Bruised, but not bloody. Definitely not broken."
Dash stood up and shook the dust off her wings. "Any landing you can walk away from, right?"
"I hear that." Derring stood up and took the torch, hitching it to a strap built into the side of her saddlebag. She looked up at the narrow hole in the center of the ceiling. "Looks like they closed it back up... we'd better look around."
"We're not seriously going to try and fix this thing, are we?"
"Of course we won't."
Dash arched an eyebrow. "Are we gonna try and break it even more?"
"Of course we will." Derring brushed some of the dust off her jacket. "Though I'd settle for finding another exit."
Dash flapped her wings and explored the upper half of the room. "I see a balcony up here, all along the wall... there's a couple corridors."
"I'm more worried about this room, right now." Derring walked to the edge of the room and began searching the walls. "There's a few inscriptions here, but they don't make any sense."
"Different language?"
"No, it's Aduu... but the words don't have any meaning. The context is all funny." She paused by a particularly large inscription and brushed away a thick curtain of vines. "The alphabet is the same, but the words are all strung together in different ways."
Dash hovered sideways, scanning each of the shadowy corridors leading off the balcony. "Any of 'em look familiar."
"Something about a storage or resting place for something important. The name reminds me a bit of the ruin where we found the prism." Derring leaned closer to the wall and squinted. "I still can't tell what sort of place this is, though... a vault or a warehouse, maybe?"
Dash glanced down at her, but gasped when she caught sight of the raised platform they'd landed on in the center of the room.
"Derring? I think it's... that kind of resting place."
Derring looked away from the wall and turned to the platform. She walked across the room and climbed up the small central pyramid built into the floor, and Rainbow Dash landed beside her. The top of the stone platform was a rectangular slab sculpted with the shape of a beautiful young mare: she was lying on her back with her front legs crossed over her chest and her eyes were closed. There were exposed grooves and slots in the sculpture along her neck, ankles and forehead. Her hair was a complicated array of loops and whorls, with long tresses that trailed down beside her and merged into the frame of the slab.
"Incredible," Derring-Do whispered. "It's the first thing we've found that says anything about the ponies who lived here."
"It's beautiful... but what about those weird grooves in her neck? Do you think it wasn't finished in time?"
Derring shook her head. "That's probably where they installed the parts that looked like jewelry. Somepony must have found this place before and stolen the treasure. That does make it harder to guess who she was or what she did."
"Grave robbers," Dash sneered. "Stuff like that belongs in a museum."
"Don't be so quick to judge," Derring said. "Technically, we're grave robbers."
"Yeah, but that's different."
Derring-Do turned to give Dash her full and undivided attention. "Why?"
She bit her bottom lip. She rolled her eyes, examining the ceiling.
"For reasons—good ones, too—that I haven't figured out yet." She tapped her hoof on the floor. "We haven't stolen anything yet! That's why!"
"Because we haven't found anything yet," Derring said as she stroked a hoof along the edge of the slab. "There's scrape marks here. There must be a mechanism of some sort to open and close the sarcophagus."
"W-w-what!?" Dash took a nervous step back. "Why would anypony want to open it again!?"
"This sarcophagus might be reserved for ponies of a particular certain rank or status, like a priestess or princess or something... whenever somepony died, they might move the old body to a more appropriate mausoleum and replace it with the most recently departed figurehead."
"Why would anypony do that!?"
"Maybe they believed in reincarnation. Maybe they thought the old priestess would live on in the body of the next priestess. Who knows." Derring went to the other side of the sarcophagus and continued searching. "Funerary rites for the rich and powerful are among some of the weirdest ceremonies you'll ever... aha! Here we go!"
"What? No!" Rainbow Dash flew over the sarcophagus and landed beside her. "Maybe we shouldn't mess around with this! I mean... it's a grave! Somepony could... they could be..." she pointed at the sarcophagus and whispered harshly. "In there!"
Derring grinned. "Exciting, isn't it?"
Dash watched as Derring pressed a small stone block concealed under the edge of the lid. Stone ground against stone and the lid slowly lifted up, supported by a series of slender metal pillars.
Derring peered inside. "Oooh! Looks like the previous grave robbers left the good stuff behind after all."
Dash stepped in place, bouncing on the tips of her hooves. "Oh, no-no-no-no..."
"Come on, you big baby. You can look, as long as you don't touch."
Rainbow Dash crept to the edge of the stone coffin and peered over the edge. Inside was the body of a pony, shrunken and shriveled to little more than a skeleton. It was covered almost entirely in dusty-brown bandages but the few exposed parts had a texture that was somewhere between an ugly scab and rotten, wrinkled tree bark.
Dash stared at it for some time.
Derring-Do pointed at a magnificent array of golden jewelry clasped around the body's neck and ankles. "Looks like the thieves couldn't get it open... still doesn't help us, though. She's wearing an awful lot of jewelry, but the style isn't very distinct and there's no emblems or symbols. Can't tell if it's royal or religious or what. We'll have to take a closer look when we come back."
Derring-Do looked up at the raised lid. "Well, well... looks like there's an inscription on the inside." She took out her journal and began making notes. "Aaaaand score! It's a map of some sort. Might take me awhile to translate it properly, but odds are good it's a map we can use."
Dash continued to stare into the sarcophagus.
Derring put her journal away and tucked her helmet down. "Hey. Whatcha thinking?"
"That's a pony," she said. "A dead pony."
"Yes. Yes it is."
Dash turned to face her, slowly. "We are standing... in a room... with a dead pony."
Derring glanced at the sarcophagus, then gave Dash a quick nod. "Seems so."
Dash sprinted across the room and ran around in tiny little circles, jumping up and down. "Ew-ew-ew-ew-ew!!"
Derring gave her a lopsided smile. "Yeah... you never forget your first time."
For the next quarter-hour, Derring-Do and Rainbow Dash walked through the twisting stone corridors beneath the ziggurat with only the flickering, greasy torch to light their way. They moved slowly, and Derring paused every few steps to examine the walls and floor.
"This is taking forever," Dash said. "Are we even using the right map?"
"It's definitely a map of this place." Derring turned the journal upside down and tilted her head. "But parts of it are all muddled. It's like each little chunk was drawn by a different mapmaker, and none of them were allowed work together."
Dash took care to step over a patch of slimy mold. "The last ruin was so clean and empty," she said, "but this place is full of vines and mold and stuff. How can anything grow down here?"
"No idea. I'm not exactly a botanist." Derring paused to look at the floor tiles. "Another pressure plate here. No wait... there's three of 'em. That's got to be the tenth set of mechanisms we've passed by. I'm going to run out of chalk at this rate."
"Hey look!" Dash pointed ahead at a huge stone wheel built into the wall. "Something tells me these aren't just traps."
"Not all of them," said Derring, "but I'm afraid we don't have time to push random buttons and see what happens." Derring made a note in her journal and continued on. "There should be a big room up ahead. It's not much—"
"Shh!" Dash hissed.
They both froze or several seconds, perfectly quiet.
"I swear I heard something behind us."
"It's just random noises. Nothing more."
Dash shook her head. "No, these sounded just like hoofsteps. They're gone now."
They continued walking for a short distance, until Dash spun around to look behind them.
"I swear I heard hoofsteps! They stopped as soon as we stopped!"
"Let's test something." Derring-Do walked in place, producing some loud hoofsteps of her own. She stopped moving and moments later, the exact same pattern of hoofsteps echoed back to them. They sounded distant and distorted.
Rainbow Dash sighed. "Well now I feel silly."
Derring-Do leaned close and whispered to her. "Don't feel too silly. The cult leader said that others had been sent down here before us. They never came out again... which means they might still be wandering around down here."
Dash nodded.
They continued on down the hallway, haunted by their own steps, and came to a large open room with a large fountain in the middle. The pool was filled with foul-smelling muck and slime, and the sound of dripping water echoed about them. The fountain was comprised of three mares with long flowing hair, all rearing up to hold a large urn in the air between them.
"Not exactly what I was expecting," Derring said as she glanced at her journal. "The map said there would be an important mechanism here... some kind of control system. See if you can find something."
Rainbow Dash flew to the far side of the room and began pulling down vines. "Whoa... check this out!" She pulled away the foliage and revealed a whole cluster of wheels, chains and pulleys.
Derring walked over and stared at the machinery. "The whole wall is one big mechanism," she said. "It looks like it continues on into the floor, too."
"Great! So how do we get it working?"
Derring-Do gave a tiny little shrug. "...Dunno."
"You dunno? What do you mean you dunno!?"
"What did it sound like I meant? I don't have the slightest clue how to get this thing working."
"But you're an archaeologist! This is your bag!"
Derring scowled at her. "Sorry. They didn't require me to take any mechanical engineering courses while I was learning to scrape dirt off broken bits of pottery."
"Yeah... I guess." Dash looked at the machinery. "Think we should start pulling chains at random?"
"You're guess is as good as mine," Derring said. "Just remember, we want to learn about this machine, but we don't necessarily want to get it working."
Dash hovered back and forth in front of the wall of exposed machinery, searching carefully. Finally, she tugged a nearby chain. Something behind the wall ground against something else, but stopped a moment later.
"Go on," Derring said, "keep trying."
Dash began pulling levers and pushing blocks completely at random, waiting just long enough for something to happen. Finally, one of the switches caused the wall to their left to open wide: behind the wall there was a huge, hollow wheel with a heavy bronze chain looped around it.
"Now we're talking!" Rainbow Dash flew over and pushed the wheel from inside. It turned only a few degrees. "Almost... almost!"
"Step aside," Derring said. She climbed into the wheel and began walking in place. She clenched her teeth and scrunched her eyes shut, straining against the massive stone weight... slowly, the wheel began to turn.
Rainbow Dash flew back to the exposed wall and watched in amazement as the tiny cogs and chains began to move. After a moment, the wheel locked into place.
"It's not budging," called Derring.
"I know, I know!" Dash's eyes flicked over the various components, searching for something out of place. She hovered up near the ceiling and tugged a switch. "Anything?"
"Still stuck."
She pushed a nearby stone button, and the wheel began to turn again. A different set of chain loops went into motion.
"Oh that's where that goes!" Dash hovered a little lower, following the path of the chain. "Dangit, I was never any good at these kinda puzzles... I wish Twi was here."
"Dash? I could use a bit of help here!"
"I know, I know. I'm working on it." Dash pointed at one of the adjacent stone cogs. "Lesse now... if that goes there..."
"Dash, do something!"
She looked back and saw the giant wheel spinning rapidly, with Derring-Do stuck inside it: She was sprinting just to keep from tumbling out of control.
"Aaah! Kay! Right!" Dash scanned the machinery and pulled another switch, then pushed two more buttons. She watched as different sections of the wall came alive, shaking off a thick coat of dust and debris. The mechanical energy fed through the machine from one side to the other, one chain at a time, until it finally formed a complete link to the other side. The walking wheel began slowing down, and mechanical noises rumbled all around them.
Derring hopped out of the wheel and brushed her mane back with a sigh. "Wasn't so hard, was it?"
"I guess I got the hang of it," said Dash "but it still doesn't tell us what this thing is supposed to..."
There was a loud sucking sound, wet and goopy. They turned to the fountain and watched as the pool of fetid muck rippled. The liquid drained out, leaving only a thick layer of plant matter, and water began pouring out of the urn built into the statue. It was dark and brackish at first, but soon turned crystal clear.
Derring-Do tilted her head. "That's... ambiguous."
The floor shuddered beneath them. Dust shook free of the ceiling, and the sound of rushing water ran through the walls and ceiling. They tensed up, but nothing happened.
Dash's left ear flipped back. "Think we should hurry?"
"Quite." Derring ran for the exit, but paused at the next corner. "Wasn't this... a left turn when we came in?"
"I guess. Why?"
derring peered around the corner. "Now it goes right."
"Well, yeah, cause we got turned around. If it's left going in, it'll be right going out."
"No, I mean..." Derring shook her head. "Nevermind. Let's just go."
They rushed through the hallways, following their map back towards the entrance. Derring-Do spent most of it frowning quizzically and turning the map sideways or upside down. Despite her confusion, they reached the central chamber without difficulty. Now, though, the room was alive with motion: the ring shaped balcony was rotating along the inside of the wall, and dozens of stone pillars were sliding in and out of grooves in the wall. A constant shower of dust and vines rained down to the floor.
"...Amazing!" whispered Derring-Do.
"Look at the water!" Dash pointed at a nearby section of wall: there was a whole maze of spouts and slides built into the bricks, and trickles of water flowed all throughout them like blood pumping through veins.
"It's like a water clock!" she said. "I saw one in the palace, once!"
Derring looked up at her. "A water what?"
"It's a machine that uses flowing water, instead of chains and gears! See all these channels?" She floated up a few yards and pointed at one of the countless tiny aqueducts. "Water flows through and turns the wheel, and then the wheel opens or closes another channel... and then the water in that channel pushes other wheels, and it just goes on and on."
"You're pulling my leg."
"No no, I've seen 'em! They have one in the palace: a silk-loom that makes sheets of cloth all by itself! It moves the thingamabob, reloads the string, and even stops the machine if you put your hoof in the way." She stared at the vast array of veins built into the walls all around them. "Except that thing was built with tiny little gears and chains. And it wasn't nearly this big.
Derring-Do stared at the vast maze of veins built into the walls. "It's a clockwork apparatus," she said, "built out of water. Phenomenal!"
"Didn't you say before that the whole city could be one giant machine, and the Prism was the key?"
"I wasn't speaking literally," she said. "My stars... the Dzunturans really were more advanced than anypony dreamed!"
Dash landed beside her. "Think we can figure out how the rest of it works?"
She nudged her helmet up. "I know one way to find out." She walked towards the sarcophagus in the middle. "But first I'd like to get another look at that map. Something's not right about it."
Dash followed alongside her. "Heh... that'd make a pretty good catchphrase, you know."
"What are you talking about?"
"You know... cool phrases characters use." Dash spoke in a deeper tone. " 'I know one way to find out!' You say that a lot."
"Twice, Dash. I've only said it twi... I can't believe I'm even having this conversation!"
They walked to the edge of the sarcophagus and looked up at the raised lid. Dash glanced down, briefly, then looked back up again. After a moment, her eyes widened in alarm.
"Derring?"
"Hold on..." Derring-Do took out her journal and made a few corrections. "This is crazy. The map leads where it says it leads, but directions like west and north are totally wrong... it's more like a flowchart than a map."
Dash tapped derring's shoulder. "Derring?"
"I guess that kind of makes sense... if the whole temple is a giant mechanism, then this must be like an engineering schematic. It's not meant to be taken literally."
"Derring... the coffin is empty."
"It's a sarcophagus," she said, ", not a coffin. Sarcophagi are usually designed to remain above ground instead of being buried. I know this one is technically deep underground but it's on display in a public area, so..."
Derring paused and looked down into the sarcophagus. The mummified body, along with all its wrappings and jewelry, was missing. They watched the empty space for some time.
"Forget about it," Derring said. She looked back at the inside of the lid. "I think I can make a little more sense of this thing... there are two other chambers nearby, with similar mechanisms. Unfortunately, I don't see any exits."
"The body is gone," Dash said. "Why is the body gone?"
"It's not our problem right now."
"How can you say that? What if..." She spun to look behind herself, eyes wide. "There! Did you hear that? It sounded like... something!"
"This whole room is full of moving machinery and running water. It's nothing."
"It sounded like something moving! Like... hoofsteps!" Dash's eyes darted left and right. "What if... what if it's... following us!?"
Derring frowned at her. "That's the most ridiculous thing I've ever heard in my entire life. And considering I've spent the last few days with you, that's quite an accomplishment on your part."
"That doesn't change the fact that the body is missing! Let's hear you explain that with your fancy-shmancy science and logic! You can't, can you!?"
Derring watched her for a moment, bored.
"Perhaps somepony moved the body while we were gone."
"Who!?"
Derring turned back to the lid. "The cult leader said that other ponies were sent down here to investigate, but we know we were the first to open to sarcophagus. They must have noticed it was open and moved the body."
"Why!?" Dash grabbed her own ears and pulled them down. "Why would anypony even do that!?"
"Because the Lunatic Cabal’s membership is made up entirely of lunatics!" Derring shouted. "Now go stand watch for trouble—real, credible threats only, please—and let me study this map in peace and quiet!"
Rainbow Dash glowered at her, frightened and furious at the same time. "Fine. Fine! But this is going to turn into a horrible nightmare, I just know it. You'll see! Any second now, a horrible monster is going to suck our organs out through our noses or something."
"Yes, yes. Now stand guard."
Dash started to turn, but froze in place. Her eyes moved to one side, ever so slightly. "Oh no... she's right behind me, isn't she? I just know she is! I'm gonna turn around, and she's gonna be right there!"
Derring said nothing.
"Right. Well. Better get it over with quick." Dash took a deep breath and flexed her shoulders. She spun around all at once, tensed for battle. Her eyes flicked back and forth, but there was nothing to see.
"Okay. All clear. I'm still alive." She walked down a few of the steps and scanned the room. "...For now, at least."
"Forgive me for containing my enthusiasm," Derring said.
Dash glanced back at Derring, who was twisting around to get a closer look at the inscription. "How can you be so dang cool about all this? Seriously." She turned back to the room just as a skeletal, desiccated body began rising up out of the stone floor. Strips of cloth slithered out from between the stone tiles and congealed into shape, while dry sand flowed up and began filling it out. The cadaver was thicker now, meatier, and the face looked only a little skeletal. It was undeniably the body of a filly, just like the sculpture on the lid of the sarcophagus. Her eyes were black, shadowy holes.
"Here, hold this." Derring passed her the torch without turning to look.
Rainbow Dash took the torch. She clenched her jaw tight and continued to stare at the mummified filly. Her lips trembled, and a tiny, choked squeak escaped her throat.
Hit her. She's right there. Just hit her with the torch and set her on fire. Do something. Anything.
"Dangit..." Derring Do leaned into the sarcophagus and kicked her legs in the air. "Can you hold me in place? There's one last spot that's impossible to reach."
The mummified filly finished congealing. A magnificent array of golden jewelry emerged from within her body, their delicate chains intertwining with the web of cloth strips. She stepped forward, moving with the grace and poise of a dancer... the body beneath the wrappings was curvaceous and nubile.
She took a dainty step towards her. She took half a step backwards, but her muscles trembled helplessly. Her throat was clenched tight. Her skin was cold and clammy under her coat. She couldn't tear her eyes away from the empty black sockets looming in front of her.
Dash's grasp went limp and the torch tumbled to the floor. "W-w-who..."
"Youmgui." Her silken voice was a whisper that reverberated from all directions at once. It was soft and smooth as a razor blade. It rumbled like a peal of distant thunder. There was a deep, metallic hiss as a gleaming black viper slithered out of her left eye socket and licked the air with it's tongue.
The mummified filly tilted her head. "Youmgui Taivan," she said.