It was getting dark as they walked through the woods towards the abandoned graveyard. Memento Maury drifted lazily through the winds as she hovered over the rest. Blackwing and Crystal's expressions were obscured by the hoods of their dark capes. Tank and Coldie walked before them, the younger sibling's gait significantly light, given the amount of various necessities she had stuffed into her saddlebags.

“Do we have to take them all with us?” Crystal whispered to Blackwing as she glanced uncertainly at Coldie, Tank, and Memento in front of them. “I mean, I appreciate their will to help, but is this a good idea?”

“They can be helpful and, like you, they deserve to know what the mayor is up to,” he answered in a similar whisper. And Luna keeps telling me to take all the help I can get, he added in his thoughts.

Memento lowered her flight so she could talk with others freely. “Are you sure that the kid's not following us again?” she addressed Coldie and Tank as she hovered right above their heads.

“He’s having a sleepover with your little brother at one of their friends tonight, remember? So yes, I’m sure,” Coldie answered. “And you could show some appreciation, after all, he saved your life last night.”

Memento shrugged. “We’re all gonna die someday anyways,” she answered dispassionately. Coldie just shook her head at her.

Soon, the familiar rusty iron fence appeared before the five ponies, as well as the tombs and monuments behind it. Night had come early as clouds crossed the sky, but the moon shone brightly through. This time, they had brought a couple torches with them.

“So you’re saying this tomb's some kind of entrance? I saw no doors inside,” Tank tried to start a conversation as they approached the supposed Steamwand’s tomb. Even for him, despite his size and strength, forgotten tombs were somewhat intimidating and certainly didn't add to his, or anypony else’s, morale.

“If it’s an entrance to tunnels that lay beneath, then the ‘door’ should be somewhere in the floor, which we didn’t examine last time,” Crystal explained.

“I don’t think the guardian runes were placed there just for decoration. They’re supposed to guard the entrance, we just need to find it,” Blackwing added. “But let’s get this thing open first, shall we?”

Just like the previous night, they placed the alicorn’s wings in a spread-out position, causing the tomb’s entrance to open, while Memento found an old stone column lying nearby. Tank, with the help of both pegasi, managed to lift it and put it upright in the entrance to prevent it from closing. The tomb's interior was filled with a warm, yellow light as Coldie lit one of the torches.

“Well, I see no floor, to be honest with ya. Only dust,” Tank pointed out as he breathed heavily after his latest feat of strength. Indeed, the floor was cover by a thick layer of dust, probably centuries old.

“Time for some cleaning,” Coldie grinned merrily as she pulled a feather-duster out of her saddlebags. She noticed slightly puzzled looks of the others. “What? This time I’m properly prepared.”

She started dusting the tomb’s interior while Tank held the torch to help her out. Gradually, she uncovered the whole floor while a large pile of dust formed in one of the corners. Thanks to Coldie's effort, a big square plate was revealed in the middle of the tomb that consisted of a number of small, inscribed stone tablets.

“Good job. Just like a professional archeologist,” Blackwing said to Coldie with appreciation.

“I get a lot of practice at home. Besides, it was easier than dusting Tank’s room,” she answered as she winked to him. “But look at this.”

They all lowered their heads to examine the new find. There were ten stone tablets with parts of sentences that formed five verses. The inscription itself seemed enigmatic to say the least. It wasn’t clear to anypony how it was supposed to be read or understood.

[LIKE A SICK EAGLE][MY SPIRIT IS]
[TOO WEAK - MORTALITY][TELLS ME I MUST DIE]
[AND EACH IMAGINED][ME LIKE UNWILLING SLEEP]
[WEIGHS HEAVILY ON][PINNACLE AND STEEP]
[LOOKING AT THE SKY][OF GODLIKE HARDSHIP]

“Another poem?” Coldie asked as she raised an eyebrow. “And I thought the first one was strange.”

“Another riddle I guess,” Blackwing said as he rubbed a hoof against his forehead, a confused expression crossing his face. “But this one just looks like some random lines to me. Like the words weren’t in the right order, or something.”

“Then let’s change the order,” Tank said as he shrugged, like it was obvious.

“We could. If we knew the right sequence and assuming that these tablets actually are movable,” Crystal stated with a frown.

“Only one way to find out.” Coldie smiled as she pulled a crowbar from her saddlebag and jammed it into her brother’s muzzle. Tank tried to say something, but the iron in his mouth stopped him. He sighed and started hustling with the first tablet. Luckily, it turned out to be movable. It took him more than a quarter of an hour, but one by one, he managed to remove all the stone tablets. Then, they all started to bustle around the pieces of text, trying to find a sequence that would make more sense. Tank was in charge of moving the heavy pieces of stone, Coldie and Crystal were matching words that rhymed with each other, and Blackwing was trying to come up with reasonable connections between parts of the sentences on tablets. Memento hovered above them all, trying to look at the whole text.

“It looks like Steamwand, or whoever actually created this place, had some serious concerns about the afterlife,” Blackwing stated as he moved tablets with “TELLS ME I MUST DIE” and “TOO WEAK – MORTALITY” together. “This is another poem about death and flying.”

“U-huh," Tank nodded as he moved the pieces. "Hold this would’ya?” He passed Memento two stone tablets with “LOOKING AT THE SKY” and “LIKE A SICK EAGLE” and she almost fell on the floor under their weight. Flapping her wings hard, Memento managed to land slowly and put the two tablets in front of her. As she looked at them, breathing heavily, she realized that the line before her sounded familiar.

“Like a sick eagle, looking at the sky.” Memento read quietly and glanced towards Blackwing’s tablets. “Tells me I must die, like a sick eagle, looking at the sky,” she read out loud. “Wait. That’s Kicks.”

Crystal, occupied with other tablets until that moment, turned around to face her. “What did you say?”

“Well, it’s true,” Tank admitted, as he nodded knowingly. “That’s why young mares like you shouldn’t drink pure gin. Mix it with soda, some juice or-“

“I think she means Gin Kicks of Moorgait; a great equestrian poet,” Blackwing explained.

“Oh, thaaat Gin Kicks,” Tank said and nodded. The siblings exchanged puzzled looks.

“That’s one of his poems. I think I remember how it goes,” Memento stated, here usual emotionless voice only slightly contaminated with excitement. "Take these two and put them together there..." She started to instruct Tank in what order he should place the tablets. The others watched as the text of the original poem was being restored. As Tank placed the last tablet, Memento began to recite it, with just the slightest hint of pride in her voice.

[MY SPIRIT IS][TOO WEAK - MORTALITY]
[WEIGHS HEAVILY ON][ME LIKE UNWILLING SLEEP]
[AND EACH IMAGINED][PINNACLE AND STEEP]
[OF GODLIKE HARDSHIP][TELLS ME I MUST DIE]
[LIKE A SICK EAGLE][LOOKING AT THE SKY]

When the last part was in place, they heard a loud screeching noise and some other sounds that indicated movement of some metal parts underground. The whole stone plate with the text sank into the floor about ten inches and slowly moved aside, revealing a steep staircase that lead into the darkness below. They all peeked inside anxiously. Coldie tried to shed some light on the stairs and the underground tunnel with her torch, but there wasn’t much they could see without descending.

“Dark tunnels, hidden under the abandoned graveyard. Maybe this trip won’t be a complete waste of time after all,” Memento stated as she grabbed one of the torches with her muzzle and started to walk down the stairs. Blackwing, Tank, and Crystal quickly followed suit.

“Yeah, what could possibly go wrong?” Coldie muttered to herself. She swallowed and anxiously walked down after the others.

After a couple dozen steps the stairs ended and their torches shed light on an entrance to a tunnel, which they entered with little hesitation. It was tight, rather low and descended mildly as the ponies moved forward. Tank had to bow his head a little so he wouldn’t hit the ceiling. The air smelled of moist and mustiness. At first the walls were made of dirt with some old, rotten, wooden stamps, but after about fifty yards or so, it began to change. The tunnel’s walls consisted more of stone than dirt, with less plant roots and less mustiness in the air. After what could be another thirty yards, the five ponies reached a fork. At this point, the surroundings seemed more like natural caves than tunnels. There were no stamps holding the ceiling, only irregular stone walls, a few stalagmites here and there, and the sound of dripping water echoing quietly. They had three ways to choose from, each of them dark and tight. Blackwing took one of the torches from Memento.

“Wait here. I’ll be back in a minute,” he said as he walked into the leftmost tunnel. The others waited about five minutes for his return. Blackwing had some bad news for them. “We have a problem. There’s another fork, not far from here. This could be a real maze.”

The other four exchanged confused looks. Coldie started to rummage through her saddlebags, which caught Memento’s attention. “Let me guess. You’ve got a map of these tunnels in your saddlebags.”

“No,” she answered. A moment later, with a smile of satisfaction, she pulled a big ball of string out of her saddlebags and dropped it on the stone floor. “I’ve got this. I hope it’ll be long enough.”

“Well, that’s better than ten shmelelogical guides,” Tank stated, a hint of appreciation in his voice as the others nodded knowingly. Coldie tied one end of the string to a thick stalagmite and the five ponies walked together into the leftmost path; Coldie unwinding the string as they progressed forward.

It was hard to tell how long they walked through the caves, maybe an hour, maybe three. They reached a dozen of dead ends and often had to go back to different forks. Sometimes they had to squeeze through tight passages or cross underground streams. They visited a couple of spacious caverns too, some over three meters tall. The string was usually long enough, until they reached some really long, straight tunnel. It seemed different from the rest of the caves, almost as if it wasn’t natural. Its floor was flatter and more equal, while the ceiling was at the right height for ponies to walk upright. They all agreed to follow that tunnel even without the string, at least to the next fork. But as they continued to walk forward, there was no fork.

“It just goes on and on; no forks, no end, nothing. And what’s with the smell?” Coldie grumbled as she wrinkled her nose.

“No visible end, no purpose, and it stinks. A beautiful underground metaphor of life,” Memento added, more to herself than to anyone else.

“It smells like rotten eggs. It’s not our food, is it?” Blackwing asked. As they progressed forwards, initially barely sensible, the smell was getting stronger.

“No, I don’t think so. It’s hydrogen sulfide, no doubt about it. Put out your torches. If there’s more gas, we could be in trouble. It’s highly flammable and poisonous.” Crystal explained. She cast a spell and the tunnel was lit by the green light from her horn. They covered their muzzles and kept walking. Soon Crystal’s horn shed light on a big steel door with a valve at the end of the tunnel.

“Let’s have a look inside,” Blackwing proposed. “Tank, would you help me with this valve? If it’s been here for years, it’s probably hard to move.” Tank nodded and they approached the door.

“Wait. I’m not sure it’s such a good idea,” Crystal said, as she grabbed Tank’s leg in attempt to stop him. “We don’t know what’s behind that door and the intensity of the hydrogen sulfide smell is already disturbing.” At this point they were all covering their muzzles tightly with various pieces of cloth they had with them or, as in Memento’s case, with wings. The smell was almost unbearable.

“Well, it’s either this or going back,” Blackwing stated firmly. “We’ll be careful, I promise.”

The two stallions grabbed the valve together and with some serious effort, they managed to turn it. They pulled the heavy steel door open and peeked inside, but the smell of gas almost literally pushed them away.

“Close it!” Crystal shouted. “And close your eyes, everypony! Now! I’m serious!” All five ponies closed their eyes shut. Blackwing and Tank managed to close the door somehow without the use of sight. “Try not to breathe too much. Let’s back away, quickly!” Crystal commanded. They all moved away from the door for what could be about thirty yards back into the tunnel. They stopped to breathe in some less polluted air.

“I think so,” Crystal answered. “Hydrogen sulfide is dangerous in high concentration like this. It can cause blindness or even kill you, if you take in too much of it that is.” She turned to address Blackwing. “Did you see anything in there?”

“I managed to get a peek inside," he answered. "A rectangular room with some vents in the floor. And a similar door on the other end.”

“The gas probably comes from these vents,” Crystal assumed. “It seems we’ll have to go back.”

Blackwing sighed. “Ponyfeathers. This must’ve been the right track. Somepony created this to defend something. Maybe the Steam Key itself.”

“You said there’s another entrance. Maybe we should go look for it?” Tank said in attempt to cheer up his buddy.

“Let’s go and find the end of that string,” Blackwing said as he started to walk in the direction they had come from in the first place.

“Wait,” Crystal said and sighed heavily. “There is a way, I think. But it’s going to be dangerous.” She seemed to be thinking very intensively.

“Let’s hear it then. You said that this ‘Key’ thing could be dangerous to all of Equestria. If it’s true, then there’s no time to lose,” Coldie stated.

“Ok. If it’s hydrogen sulfide, it can be decomposed if it reacts with oxygen. With that amount of gas, it would take some time, but I could catalyze the reaction with my magic,” Crystal explained anxiously.

“It’s not that easy. First, I’d have to use up a lot of oxygen from here and that would make it hard for us to breathe. Second, the decomposition of hydrogen sulfide gives us hydrogen dioxide which is bad news, because it’s poisonous as well,” Crystal explained. “Luckily we get water from the reaction as well, in similar amounts. And that’s good news because they mix together easily and also I could magically accelerate this process as well. That would give us sulfurous acid all over the place.”

“Bad, but still a lot better. First, sulfurous acid, contrary to the sulfuric acid, is weak and much less corrosive.” Crystal paused and looked around. It was satisfying for her to see others listening to her with hope instead of the distrust and prejudice she usually experienced from the majority of the citizens of Shadington. She continued in a more confident manner. “Second, since it’s a liquid, it will most likely go down the vents in the floor, leaving at least parts of the floor dry. And third, some of us have wings, right? That could give us the possibility to reach the other door and leave the room.”

“Oh, Crystal. You’re good.” Blackwing said as he grinned widely. She gave a small smile back at that.

“If you’re sure about this...” Tank said hesitantly. “Just tell us what you need done.”

Crystal put on a serious expression in an attempt to look more confident. “Boys – I need you to open the door,” she instructed. “When it’s open, I want everypony to keep their eyes closed and hold your breath until I tell you otherwise.”

There were some anxious glances between the siblings and Memento, but finally everypony nodded in agreement. They approached the door, surrounded by the unpleasant smell. Tank and Blackwing opened it again and everypony followed Crystal’s instructions. While they held their breath and kept their eyes shut, she concentrated on her spell. Crystal’s horn glowed, and they all felt the air moving around them towards the door. Then, for a fraction of a second, the tunnel and the room were lit by a flash of green light, faintly visible even through their closed eyelids. The smell of rotten eggs started to fade towards more bearable levels and they heard a sound of thousands of drops falling to the floor at the same time.

When the four ponies opened their eyes, they saw the dark room in front of them, lit up faintly by Crystal’s horn. There where pools of acid everywhere on the floor, with a few dry spots spread around. Just as Crystal predicted, most of the acid had run down the vents in the floor.

“You two, fly there and open that door,” she addressed the pegasi. Her voice was subdued, as she was covering her muzzle with a flap of her cape.

Memento and Blackwing did as Crystal told them. They flew to the other door, but the valve was wet from acid. Blackwing took off his cape and wrapped the handle with it. They grabbed the valve together through the cloth and with supreme effort, hindered as they were trying not to breathe too often, they managed to move it and the door opened. Then, they helped Crystal and Coldie reach it, lifting them over the biggest pools of acid. while Tank managed to jump from one dry spot to another. When they all got outside of the room, he shut the door as quickly as possible. They found themselves in another tunnel, but this one didn’t resemble a cave by any standards. It had a brick floor, and walls with places to put the torches in, and an arched ceiling.

“It’s safe to breathe now, I think. Everypony okay?” Crystal asked as she looked around at the others with an expression of concern crossing her face.

“Fine, thanks,” Coldie answered, a little warmth and gratitude in her voice, something Crystal hadn’t heard before from any of the siblings. “Where are we anyways? Somepony’s cellar?”

“I wouldn’t be surprised,” Blackwing said as he glanced into darkness, smiling inscrutably.

“I very much appreciate sacrificing your fancy coat, but what in the name of Celestia do you have on your back!?” For the first time, they all heard an actual surprise and some fear in Memento’s voice as she addressed Blackwing. She stared, apparently disgusted and a little terrified, at the creature that was no longer hidden under his cape.

“Oh.” Blackwing turned to look over his shoulder. “That’s Cameron,” he said as the chameleon waved to Memento.

“A lizard,” Memento stated firmly. “I don’t like lizards,” she said as she backed away from him. Blackwing shrugged, and so did Cam.

“Come on Mem. Look, it’s so cute!” Coldie grinned widely as she tried to stroke Cam’s back. Apparently she didn’t convince Memento, who kept looking at the chameleon with utter disgust.

“So, you carry a chameleon named Cameron everywhere you go?” Tank asked as he raised an eyebrow.

“Not everywhere,” Blackwing answered. “And yes, ‘Cameron the Chameleon’. The previous owner used to call him ‘James’, but that sounds silly.”

"I think it's great that your spirits are up so you can chit chat merrily despite the danger we've faced; but since none of us seems to have suffered any severe acid burns, nor gas poisoning, I suggest we move on," Crystal proposed impatiently. She was still breathing heavily after her last feat of magic and they could all see big drops of sweat on her forehead. "If I remember correctly, we decided to follow this path because there was no time to lose."

"You sure? We're all fine and dandy, but you look mighty tired," Tank pointed out. It was his turn to express some friendliness and concern for the infamous herbalist.

"I'll be all right," Crystal answered as she smiled faintly at the big stallion. "It's just a lot of spell casting in a very short time, something I'm not used to since I moved to Shadington."

The group proceeded onwards, keeping to a slower pace than before. Crystal's horn gave them some faint green light, but only enough to see for a couple of steps ahead. She was tired, but they wouldn't need more light anyways, they were trying to proceed rather stealthily. The smell of rotten eggs slowly faded with each step, and even with great amounts of dust rising from the floor into the air by their hooves, it was still a lot easier to breathe. The tunnel took a couple of right and left turns, but soon they approached another metal door. This one had no valve, knob, or anything to grab in general. Blackwing inspected the door closely.

"If there was a keyhole or something like that, Cam could try and pick the lock," he muttered, mostly to himself. "Crystal, I know you're tired, but maybe you could try opening the door with magic?" Blackwing still had Sprocket's clockwork toy in mind.

"I'm sorry. A better wizard probably could, but I'm not good with mechanisms," Crystal answered as she threw him an apologetic look. "If I knew or understood the construction of this particular lock, then maybe I could try, but otherwise I can't help you." She looked down at the brick floor and the green glow of her horn faded slightly. Blackwing found it hard to understand how, after all of her accomplishments, the recent one included, Crystal still thought herself to be a lousy wizard.

"Hey, don't you worry girl. You did mighty lot today and saved us in a way I don't even understand," Tank said as he approached her. He put a hoof on her shoulder and offered a reassuring smile. Crystal smiled faintly back. "It's just a door. Why don't we just give it a little push?"

Tank leaned against the door and pushed. Blackwing thought that in his place he would prefer to use his hind legs, but the big earth pony had some exceptionally muscular forelegs, something more typical for minotaurs and bears rather than ponies. After a few pushes the door bent inwards a little, but remained in place. On Tank's request, Blackwing joined him and after few more minutes of pushing and ramming the door with their bodies, they felt it break from its hinges. With a loud, echoing thump, the two stallions collapsed with the doors and anything that was behind it inside another room. Cameron jumped off Blackwing's prone body and brushed some dust off of his shoulders and back.

"So much for being stealthy," Memento grumbled as she flew inside, above the scramble of bodies and furniture lying on the threshold.

When the two stallions stood up, they could see that not only they had broken through the door, but also some big cupboard that had been full of something that looked like old laboratory glass, now turned into shards. The piece of furniture had apparently been placed against the door, most likely to hide the entrance or to prevent somepony from getting in. Coldie found some old candles and lit them to give off more light. The room was oblong and quite big, with a ceiling at the height of about six or so meters. Curiously, there was no other door visible anywhere. The room was filled with various laboratory equipment, glass, some containers, tables, chairs, bookshelves, as well as some maps and drawings hanging from the walls. These were equine anatomy studies - muscles and skeletons drawn with supreme precision to reveal every little detail of a pony's body. Apart from huge amounts of dust and the destroyed cupboard and door, everything else seemed to be in place, as if somepony had cleaned the room and left, centuries ago. The five ponies spread out around the room, looking for anything important or interesting.

Blackwing looked at the rammed door and furniture in front of him. He found it hard to believe that with his help, Tank could take down a heavy, barricaded iron door. He approached Tank, who was inspecting some maps lying on a desk near the entrance. "Nice work with the door. And with Crystal, that was really nice of you," Blackwing said, lowering his voice. "I thought you didn't like her."

"I just can't stand the sight of a sad girl. It's heartbreakin'. 'Sides, I think I could've been wrong 'bout her," Tank explained, lowering his voice as well. He glanced at Crystal, who was inspecting some bottles of long-outdated chemicals nearby. "The fact that she's cute don’t hurt either."

Tank's remark surprised Blackwing a little. As Crystal was a few years older than him and more importantly because he had other things on his mind, he didn't think about her that way. However, he had to admit that she was quite a good looking, slender mare, probably about the same age as Tank. Blackwing chuckled slightly and gave his friend a knowing smile.

"Nopony move a muscle!" Memento exclaimed suddenly, and everypony froze in their places. "We didn't pay attention to the floor. Again." She was hovering above the floor, looking down with an expression grave even for her.

"What do you mean Mem?" Coldie asked as she raised an eyebrow. She looked around herself, inspecting the floor, but apparently failed to notice anything special about it.

"Did anypony stand or walk there?" Memento asked, as she pointed a hoof towards the far corner of the room, where some crates were stacked. When the others shook their heads in unison, she pointed another place, next to a bookshelf. "And there?" Again, the rest shook their heads vigorously. "And of course none of you have laid a hoof here," she guessed, pointing at the floor below her. "Then we have a problem."

"Would you please explain?" Crystal addressed her, a concerned expression crossing her face.

"There are hoofsteps in the dust, all over the place. Fresh and apparently not ours," Memento explained. The others exchanged some worried looks and Coldie had to suppress a yelp.

"In that case, let's stay alert and look for a way out of here. There's not much else we can do," Blackwing said, glancing over his shoulder towards the rammed door and the dark tunnel behind it.

The five ponies continued inspecting the room, but there was nothing that resembled any kind of exit. They looked behind and under the furniture and they examined the walls as well. Finally Tank found something.

"Eh, sham. Come, take a look," he addressed to Blackwing. "Doesn't look like door, but could be 'nother puzzle."

He was pointing at a rectangular mosaic embedded in the wall that had been covered with a stack of some crates he had removed. It depicted the map of Equestria; or rather the continent Equestria was in. There were no borders, nor names on it; but landmarks such as rivers, mountains, and seas were present. Also, there were three holes in it that looked like places for some missing stones of the mosaic. A Closer look however, revealed them to be rounder and deeper, as if shaped for something specific to be placed in them. Coldie, Crystal, and Memento joined the two stallions staring at the wall.

"All right. A map," Blackwing said slowly, a confused expression crossing his face. He sat on his rump in front of the mosaic and contemplated the image as well as the holes in it. He sat like that for a couple of minutes in silence, with only quiet sound of a ticking clock audible, probably Tank's pocket watch.

"Like what?" Memento asked as she hovered above her childhood friend, her forelegs crossed on her chest.

"Hmm. I used to work on a steamboat when I was younger," Tankard started and the others looked at him with a mixture of interest and confusion. "Usually, we plied up and down the river, but sometimes we had an assignment in the open sea."

"I love marine stories, but perhaps we should—" Memento tried to interrupt Tank but Crystal shushed her.

"We used local maps and simple navigation devices, but our captain told us 'bout some methods they use on big vessels and airships," Tank continued. "They use some fancy magic and special maps, but the idea is rather simple. If you have three points and you know the distances from those points to one place, you can find the precise location of that place."

"GPS: Geometric Positioning Sorcery. Probably the greatest magical invention in the history of transport," Crystal recited. "Interesting. If this is Steamwand's laboratory, it could be one of the oldest GPS maps in Equestria."

As Coldie still showed a rather blank expression, Blackwing took his turn explaining the idea, beginning with a deep sigh. "You put three enchanted objects, stones for example, on the map. Those stones represent some points of known location. When the three stones are together, each of them casts a glowing circle around itself. The place on the map, where the three glowing circles intersect is the point of interest."

"Glowing stones. Sounds cool," Coldie admitted. "But if this map is for that GPS thing, then why—"

"We've got company!" Memento exclaimed and everypony else turned around. She pointed a hoof towards the ceiling. There, in something that seemed like a hatch, they noticed a head of a pale yellow coated unicorn stallion with a red and white mane, beard, and moustache, wearing a monocle.

"Mayor Steamhorn?" Coldie was flabbergasted. Apparently, until that moment she hadn't been convinced that the mayor could really have anything to do with their search and the legendary artifact. In response, Steamhorn disappeared and shut the hatch behind him.

"Get him!" Blackwing shouted. He and Memento dashed simultaneously towards the ceiling and managed to reach the hatch before Steamhorn could seal it for good. The ceiling was so high that the light from the candles didn't expose the hatch and none of the five ponies had thought about searching for an exit above their heads. Blackwing and Memento managed to move the valve and open the hatch. In a second, both pegasi flew through it and disappeared, leaving Crystal and the siblings below.

"What do we do now?" Coldie asked, still shocked. Meanwhile Cameron, left behind by Blackwing, approached her and prodded her foreleg. Coldie helped him mount her back and when the chameleon found himself a place in her saddlebags, she continued. "Should we follow them, or stay here and examine that GPS-thing?"

"Then I have an idea," she said with an inscrutable smile. "But first we have to get out of here."

"We could try stacking some furniture under that hatch or somethin'," Tank offered.

"Oh, Tankard, there's no need for that," Coldie said as she threw him a patronizing smile. "That cider you drink must be getting really hard on your head if for one second you thought that your sister would've left the house for some crazy adventures and forget to take a few yards of strong rope."

Blackwing and Memento raced up a broad shaft with a metal telescopic ladder attached to its wall. Even if they had time to stop and expand the ladder to the room below, a thick, rusty chain and heavy padlock would have prevented that. It seemed that somepony had wanted the laboratory sealed. Both felt pretty sure that they could catch Steamhorn before he could escape the deep shaft, but unfortunately, a second before they reached him, he looked over his shoulder and as he saw the determined pegasi right behind him, he cast a teleportation spell and disappeared in a flash of green light. For a second they stopped and exchanged puzzled looks, but the unmistakable sound of four hooves in a gallop not far from the shaft's exit above, indicated that Steamhorn hadn't gotten far. Apparently, he wasn't very skilled in teleportation spells. Memento and Blackwing resumed their chase.

They flew out of the shaft and exited into some small dark room, with a demolished wall. The huge hole apparently had come just recently, as a big hammer and a pickaxe were laying on the floor next to a pile of rubble. Memento and Blackwing flew out of the room following the sound of hoof steps to find themselves in something that looked like a cellar. They dashed through it and up the stairs leading to the hall and the door outside, which had been left open. They could see through the hole and saw Steamhorn turn left into a backstreet and disappear. When Memento and Blackwing left the building they realized where they were; they were by the end of the Dockers' Street, right at the doorstep of Steamhorn's house.

"I know the town better. I'll follow him on the ground so he doesn't hide from us," Memento said in one breath. "You should follow him from above."

Blackwing simply nodded as they split up. Memento disappeared down the same alley Steamhorn had taken a moment earlier and she dove into the maze of old, narrow backstreets. Blackwing soared up in the air and took a good vantage point. The chase seemed to be getting complicated. Even with the almost full moon shining brightly, the town was still very dark, making it easy to hide. From above, he noticed Memento dashing in a crazy zigzag through the alleys, but there was no sign of Steamhorn. Blackwing followed Memento's trail when suddenly, he noticed a flash of green light in some shady backyard she'd just passed by. A fraction of a second later another green flash was visible a block away. Blackwing shouted to Memento, pointed the direction with his hoof, and immediately followed it himself. However when he got there, the unicorn was gone.

Steamhorn could teleport and apparently knew the town's topography perfectly well, but he was probably twice the age of Blackwing and Memento and, of course, he couldn't fly. Running through the streets had to be exhausting for him. However, against all odds, he continued to elude both pegasi. Blackwing couldn't even distinguish any apparent direction in which Steamhorn was headed, apart from the fact that they gone from near his house towards the central parts of Shadington, the old town. He drove through the alleys left and right and each time one of his pursuers managed to spot him, he simply disappear immediately. There were no more green flashes - apparently either he was too tired to perform the teleportation spells, or had learned that it only drew their attention to him.

Each time Steamhorn disappeared down another backstreet, it took longer to spot him again and after over twenty minutes of flying to and fro above the old town, Blackwing almost lost his hope of catching the impostor. Then, suddenly, he noticed the green flash of the teleportation spell a block away from the alley Memento was dashing through and then another flash at the town square, near the big white building towering above the rest of the old town.

Blackwing turned towards Memento and shouted at the top of his lungs, waking several citizens accidentally. "THE TOWN HALL!"

Crystal, Coldie, and Tank hurriedly trotted through the sleeping town. At times, they could spot Blackwing as he soared above the rooftops, while Memento seemed to have disappeared somewhere. They didn't exchange a word the whole way, not until the docks were in sight.

"I think we should've helped Mem and Blackwing," Coldie stated between deep breaths, as they slowed down. "I trust them and all, but it didn't look like they had any luck finding the mayor."

"Blackwing and Miss Maury can fly around town chasing after that Steamhorn. Eventually they'll succeed. They have wings, for Celestia's sake!" Crystal pointed out. She was breathing heavily as well. They had run the whole way, and she had been tired even before they had left the laboratory. "Hopefully we will catch the other Steamhorn."

"Yeah. That's the part I don't get," Tank admitted, as they walked towards the pier. They could spot a couple of dockers, apparently waiting for the steamboat to approach.

"Blackwing says that Steamhorn doesn't live alone, but we know he has no family here. Also, he can apparently be in Shadington and Balefast simultaneously," Crystal explained patiently as she wiped some sweat from her forehead with a flap of her cape, now partially destroyed by the acid and rough treatment in the caves. She looked Tank in the eyes. "Don't tell me you can't put two and two together."

"But if there were two Steamhorns, we would have noticed, wouldn't we? He’s been in Shadington for many years," Coldie pointed out, an incredulous expression crossing her face.

"There are such things as doppelgangers and twins. Perhaps they were hiding really well. Otherwise, the mayor never left to Balefast," Crystal stated. She focused her eyes on the river and noticed the shape she'd been looking for. "And we're about to find out. The steamboat is closing in."

They could all see the large frame of the ship, and soon they could also hear its steam engine working, as it slowly approached the pier. Finally, the steamboat came to a halt as it hit the bumpers hanging along the jetty. They could see the sailors bustling around the deck with the moorings as they threw them towards the dockers on the pier. The gangway was lowered and a moment later, Crystal and the siblings saw the familiar, pale yellow-coated, slender unicorn stallion with a red and white mane, moustache, beard, and tail. Steamhorn was wearing a frock coat, a bowler hat, and a monocle. Slowly, he trotted down the gangway, levitating an umbrella and a suitcase in front of him. He came to a sudden halt, when he noticed the trio waiting for him on the pier.

"Well, I certainly didn't expect a welcoming committee, especially not at this hour," Steamhorn said, smiling nervously at Crystal. "Good evening Miss Vial, Miss Pint, Mister Tankard," he added as he repealed his hat courteously. Tank returned the gesture with his cap and Coldie curtsied politely, however her expression was as if she'd just seen a ghost.

"Good evening. You have some rather important things to explain sir," Crystal replied as she threw him a cold, piercing glance.

Steamhorn looked around a little nervously. "Maybe in the morning? I'm terribly sorry for keeping you waiting here at such late an hour, but right now I think we all deserve some sleep. How about we meet tomorrow and then I'll answer any questions you may have—" A loud noise, coming from the direction of the old town interrupted him. It sounded like a mixture of howling and buzzing.

"That's the siren at the top of the town hall tower," Coldie stated. "What is it, a fire?" Everypony on the pier and the sailors on the deck glanced around, exchanging worried looks.

"What do you know, I leave for a couple of days and the whole Shadington is already falling apart, ha-ha," Steamhorn said as he threw them an obviously fake smile. "I think I'll be on my way then. I must look into this immediately," he added as he started walking towards the town.

Tank moved to block his way. "M' afraid I can't let ya do that sir," he said as he reached towards Steamhorn with his foreleg. The mayor frowned, his horn glowed and Tank's hoof met only air as he disappeared in a flash of green light. Crystal and the siblings looked around in confusion just to spot him behind them as he ran towards the town square.

"Get him!" Crystal shouted as the three of them raced after Steamhorn. As he ran, he threw away his umbrella and the suitcase. The latter opened as it impacted with the pavement and the whole street was suddenly sprayed with papers, blown by the late evening breeze.

Even though Crystal and both siblings were significantly younger than Steamhorn, they couldn't gain on him. He had been well rested, while they were all tired after their underground adventures. They turned right, onto Sawyers' Street, which lead straight to the town square. As the chase closed in on the town hall, they passed by more and more ponies woken up by the siren. Some were already readying buckets of water or medical supplies, as they suspected that fire or some other disaster had happened.

By the time they reached the town square, the three ponies were finally gaining on Steamhorn. The whole place around the town hall was filling with curious and worried citizens of Shadington. To her discontent, Coldie spotted Sprocket and two of his friends there, squeezing between bigger ponies to get a better view. They must have snuck out to see what was happening, just like the adults, she guessed. In her thoughts, Coldie cursed foals' curiosity and forced herself to run even faster, straining her muscles to maximum.

Crystal dropped out of the chase, as it seemed that the siblings were quickly gaining on Steamhorn at this point and Tank would reach him with his hooves in the next couple of seconds. However, at town hall's doorstep, when the big stallion almost had the unicorn within reach, there was a flash of green light and Steamhorn teleported out of their field of view again. The siblings exchanged quick glances and Tank ran inside the town hall, while Coldie trotted back towards Crystal, who sat on the pavement, trying to catch her breath.

Gradually more ponies entered the town square and Crystal spotted some of her customers and even the irritating secretary from the town hall's front desk. The bystanders were exchanging their ideas about what happened and some even accused Crystal and the siblings of attempting to harm the mayor. Crystal and Coldie noticed the two familiar pegasi circling around the town hall tower. Apparently Blackwing noticed them as well, as he lowered his flight and gently landed on the town square near the two mares.

"Tank ran inside after Steamhorn. The other one, I mean," Crystal explained. "Perhaps the siren was their signal or something."

"Oh. So there really are two of them," Blackwing said, a little surprised that the theory about there being two mayors was indeed true. Crystal nodded in response. "We've been chasing the first Steamhorn for some time but he barricaded himself upstairs."

"What do you mean two? The mayor barricaded himself?!" An irritated voice interrupted them. It was the town hall secretary who stood nearby, listening to the whole conversation.

"There are two Steamhorns in Shadington and neither of them are real. They're impostors," Crystal explained to the flabbergasted receptionist. The herbalist couldn't fight off the feeling of satisfaction at the look on the other mare's face.

"And one has magically sealed the door to the third floor," Blackwing added. "And all the windows at that height have bars for some reason. Would you be so kind as to tell us what is so important on the third floor?"

The mare blinked in surprise. "Nothing. Everything from the third floor up is closed because the town hall has just a few employees. We didn't need that much space. We only work the lower floors and the rest simply isn't used. I don't think anypony has been up there in years."

Blackwing and Crystal exchanged worried looks. "I don't like where this is going," he stated.

"You should follow my brother. Perhaps together you'll manage to break down that door," Coldie proposed. Blackwing nodded and turned towards the town hall's entrance.

However, before he managed even one step, a loud, ground-shaking noise startled him and everypony around. It was as if somepony was trying to drive a locomotive inside the town hall's top floor. Memento, who had been flying around that height, backed away and fluttered to a greater distance from the building. The bystanders on the square started to move away, creating a big circle with only Crystal, Coldie, and Blackwing inside. Then, the town hall's dark red roof started to move. To the surprise of the speechless crowd, two parts of the roof started to open, as if it were a huge cardboard box. Some citizens exclaimed their surprise and fear at the scene while others simply watched in a terrified awe. The roof opened fully and a big, round, grey object slowly emerged from the building, like a huge devil in a box, moving in slow motion.

Memento, who had a lot better vantage point high in the air, dove towards them and stopped to hover right above Coldie's head. "It's an airship!" she exclaimed, trying to outshout the combined noises of working engines and terrified crowd.

As more of the shape emerging from the town hall became visible, everypony could see the big, crimson ellipsoidal balloon, the shrouds attached to it, and its vertical and horizontal stabilizers. Blackwing had seen a lot of balloons, zeppelins, and air yachts back in Canterlot; he knew it couldn't have been a big airship, given the size of the balloon, but it was easily big enough for a pair of unicorns. More importantly, as Blackwing realized, the small and light airships could be very fast and agile compared to the bigger flying vessels. If the Steamhorns had managed to equip their machine with a powerful engine, they could quickly fly away in a couple of minutes.

Blackwing joined Memento as she hovered above the town square and together they headed for towards the town hall's open rooftop. Then, suddenly something cracked in the roof-opening mechanism, and the two moving parts froze in place, stopping the balloon from breaking free. The pegasi accelerated; this could have been their only chance to get at the impostors. Then, suddenly a lot of things happened.

The mechanisms responsible for opening the roof started to sound again, howling a lot louder than before, but with no effect. Then, a deafening explosion racked the whole town square. The roof started to fall apart as the airship began rising again. It was shaped like an aquatic vessel, possibly to be able to land on water. The design was very simplistic, without any decoration, just wooden planks with brass fittings. The two Steamhorns were visible on the deck as they manipulated brass levers and the steering wheel.

As the roof disintegrated, tiles, beams, and even brick pieces of various sizes scattered everywhere through the air, showering the square below. Fortunately, by this point most of the scared citizens had moved away from the town hall so they were mostly safe. The only exceptions were Crystal and Coldie, who were trying to escape the square, dodging to and fro as pieces of wood and brick falling from the sky.

The explosion struck the two pegasi in the air most. They were blown away from the building and both struggled to stay in the air. As Memento managed to regain her balance, a large piece of tile hit her in the head, knocking her unconscious. Blackwing noticed that and as her senseless body fell, he dove right after, ignoring various objects hitting him on the way. He managed to grab her a good three meters above the pavement and pulled out of the dive with little effort. He had never been the most agile or the fastest of fliers, but his broad wings served him well whenever he needed a lot of lifting force. After he landed safely among the onlookers and set Memento's unconscious body gently on the pavement, Blackwing noticed that not only was the airship already escaping, but Crystal and Coldie were still in the range of the falling debris. Then, completely exhausted from the last couple hours' exploits, Crystal stumbled on some hole in the pavement and toppled. Coldie tried to help her up, but a huge, pony-sized piece of roof was already falling right towards them. To his horror, Blackwing realized that he had absolutely no chance to reach them in the mere fraction of a second they had left.

Then, out of the corner of his left eye, he noticed somepony step forward from the crowd and the air began to flicker with magic. With a blinding flash of orange light, a magical barrier materialized around Crystal and Coldie. The big piece of roof smashed right into it with an immense force, disintegrating into countless splinters and pieces of rubble. The two mares glanced around in confusion just to see Sprocket standing in front of the crowd with his horn aglow and the most determined expression a little colt could have. Blackwing smiled as he noticed another little flash of light, this time around Sprocket's flank.

The last pieces of bricks and tiles fell to the square as the airship sped off, its propellers generating so much force that any pegasus trying to approach the vessel would be tossed away. Soon, the airship was just a spot in the dark night sky. In the meantime, Sprocket's spell faded and he fell to the pavement, exhausted. Then he noticed an image of a couple of brass gearwheels surrounded with a cloud of magic, his newly acquired cutie mark. He was back on his hooves immediately and running towards his friends to show it.

Tank emerged from the town hall's main entrance and trotted towards his sister and Crystal. He had a couple of bumps and bruises, but otherwise he seemed all right. Meanwhile, somepony from the crowd managed to wake Memento up with a bucket of water initially prepared in case of fire. She scowled at the crowd around her as she brushed the wet black mane from her face before she and Blackwing joined the siblings and Crystal.

Tank couldn't believe what he heard about the events outside the building. "Not only does Sprocket do magic, he got his cutie mark too?! Dear Celaystia, there's gonna be a lot explainin' when Gearbox comes back!" he laughed thunderously.

"'Been chasin’ Steamhorn all the way up to the closed door. Then he teleported inside so I had to ram the door to follow him," Tank explained, in a manner that suggested that ramming magically sealed doors was as easy as cracking dry twigs. "When I got there, the roof was open, there was this airship, and they were starting the propellers right in me face!"

Both Coldie and Crystal gasped in horror. "And what did you do then?" Crystal asked with an expression of a little filly reading a Daring Do novel. Both stallions had to suppress a chuckle.

"Returned the favor. I grabbed some steel beam and put it in the gears of their roof-opening thing," Tank replied with a smug smile. "I think they must've blown its engine, trying to force the thing to move. You heard the explosion."

"Heard and felt it as well," Memento added as she massaged the spot on her head where she’d been hit. "Tell me, how did I end up on the pavement, alive?"

"I kind of, um, caught you and put you on the ground," Blackwing explained, smiling timidly.

Memento looked down quickly to hide her cheeks flushing. "That was... very nice of you. Thank you."

"I can't express how glad I am that nopony got hurt," Crystal stated, "but it's a shame that the Steamhorns or whoever they really were, escaped. We don't even know where to look now. With that airship, by tomorrow they could be anywhere."

"If we're lucky, they're not gonna be anywhere but at one of those three places from the map back in that laboratory," Blackwing replied. "We need to search their house. There might be some clues there." He started to walk away slowly.

"Hey, where are you going?" Coldie asked as she raised an eyebrow. "We have no chance of following that flying ship, what are we gonna do?"

"I'm going back to your house. I have a letter to write," Blackwing answered patiently. "Princess Luna needs to hear about all of this right away."

Clockwork City

by achu

Deep Below, High Above