The first thing Twilight felt that morning was a hoof on her shoulder, shaking her awake.

“C’mon, Twi, we’ve gotta get off the train.”

She opened her eyes and was greeted by a bleary-eyed Rainbow Dash. “G’morning,” Twilight managed to murmur.

Rainbow smiled. “Oh, good, you’re up! We really gotta skedaddle—c’mon…”

Twilight rose and quickly packed a few things back into her saddlebags before sliding them onto herself with her magic. Rainbow was already ready by the time she was done, so they together went out the door. Ponies filled the train car hallway, rendering them immobile in either direction. They were forced to wait as, slowly but surely, the line in front of them moved forward and off of the train; once Twilight and Rainbow finally set hoof outside in the fresh air, it had already been nearly ten minutes.

The Manehattan train station was much larger than the one in Ponyville; rather than a traditional-looking station as in many of the small towns that Twilight had visited, it was more of a covered brick expanse with several tracks leading in, so that multiple trains could stop there at once. Ponies walked around in all different directions, spread throughout the station; although there were many ponies, there was also lots of space in between them. Twilight and Rainbow walked over to the other side of the station, weaving their way between the groups of ponies.

“Hey, Twi?” Rainbow said loudly over the noise of the crowd.

“Yeah?”

“Do you know exactly where we’re going?”

“Oh, yes, the princess said that we should just wait outside the station because she’s sent a member of the Royal Guard who was stationed here to come escort us to the City Hall.”

“Cool beans,” Rainbow Dash replied.

They continued in silence across the rest of the station and quickly they found themselves descending down the brick steps and onto the sidewalk. From there, they found and sat upon an old wooden bench adjacent to the busy street that sidewalk flanked, feeling a breeze as carriages sped by. No escort of Celestia’s Royal Guard was anywhere to be seen, but a large clock tower across the street confirmed that it was only 9 in the morning—a good time to wake up, for sure, but earlier than they had been expected to arrive. They kept waiting.

As the minutes passed, Twilight’s eyelids grew heavy. She closed her eyes. A moment later, Rainbow’s voice resounded loudly in her ears. “Twi, I think you’ll wanna see who’s come to escort us.”

She opened her eyes again, revealing a burly white stallion with a navy blue mane and a similar-coloured shield cutie mark with a pink star on top. “Hey, Twily!”

“Shining Armor?” Twilight gasped. Her face lit up and she wrapped her hooves around him. “My B.B.B.F.F.! I haven’t seen you since the wedding!”

Shining Armor returned the gesture. “Heh, yup, it’s me alright. The princess sent me to take you mares to see the mayor at City Hall.”

“But how come you’re all the way out here in Manehattan?” Twilight asked. “Weren’t you and Cadance just on your honeymoon?”

“Right you are, little sis, but duty calls… though thankfully we were able to get back home to Canterlot before I had to leave again.” Shining Armor took a deep breath. “Really it was Queen Chrysalis and that nearly-successful changeling invasion that really got Celestia and Luna to up the guard throughout Equestria. I dunno if I’m really supposed to be talking too much about it, but it seems that the princesses think that there might be changelings stationed in Equestria’s major cities. Some of the other guard leaders and I were sent out to the different cities to investigate, and Manehattan in particular is important because of the disappearances.”

“Does that mean that the princesses think that the changelings have something to do with this?” asked Rainbow Dash.

Shining shrugged. “I don’t think they’re certain, but the timing is so close that it seems hard to believe they’re not related.”

“Hmm…” said Twilight, deep in thought. “Well, let’s head over to City Hall while we talk about it. I’m curious to see what the mayor says about all this.”

“I was wondering about that myself, to be honest,” said Shining Armor. “No offense, Twily, but I’m not really sure what you can do that would help our investigation that our own mares and stallions can’t do.”

Twilight smirked. “None taken. I know that the royal guardsponies are quite capable; it’s their job, after all.”

Shining Armor and Twilight Sparkle continued to talk as they walked along the sidewalk, discussing the state of the city since Shining Armor’s arrival, and what Twilight had been up to after the wedding. Rainbow Dash followed slightly behind, walking around and looking in different directions. Although the pony-filled streets of the metropolis seemed often more warm and organic than what she was used to, Rainbow also noticed something slightly off about the city’s general vibes. She felt a wave of cold rush over her and she shuddered as she looked across the street at the skyscrapers, an uncomfortable and unsettling taste in her mouth. Rainbow Dash swallowed.

“Good morning, Ms. Sparkle and Ms. Dash. It is a pleasure to meet you both, though I would have hoped that it could be under… ah, under more happy circumstances. My name is Quick Wit, though you can just call me Mayor Wit or Mr. Mayor for short.”

The mayor’s office was large and round, with high ceilings and windows that overlooked Manehattan’s tourism district. In comparison to the pragmatic simplicity of the City Hall in Ponyville, it seemed to Twilight that the ponies of Manehattan put more pride in excess and surface-level splendor in an attempt to emulate Canterlot, the nation’s capital and the height of fashion and riches. Expensive-looking trinkets lined the shelves on the left and right walls, leaving only spaces for the various accolades, trophies, and certificates that the city and mayor had achieved and won. On the wall above the large windows, behind the mayor’s desk, were the prized Equestrian City of the Year awards for four of the past five years. Even the tassels on the sitting pillows were woven from golden and silver thread.

The mayor himself, despite his flashy attitude, seemed modest in comparison; his fur was a light grey and his mane was a darker shade, and it lay loosely, unkempt, on his head and neck. His horn poked up through his mane, though it could easily have been hidden with more fluff. He wore a simple black suit, and his face looked young and fresh. From what Shining Armor had said, the mayor had only been on the job for a few months at most, but the way he presented himself was easily apparent as an attempt to discourage any thoughts about his lack of experience.

“Now, I’m sure that the princess and Captain Armor here have briefed you on the situation. Basically, even we don’t know too much about what’s really been happening or who’s behind it; otherwise we could’ve easily resolved the situation ourselves,” he explained. “What we do know, though, is that there have been four known disappearances of ponies in the last month, all pretty close to the fishing and cargo district and the surrounding beaches.”

“Four?” Rainbow Dash interjected, jumping up from her pillow where, just moments before, it looked like she had nearly fallen asleep. “But Shining Armor told us when we were walking over here that there had only been three!”

Mayor Wit grimaced. “Another little filly disappeared from the docks this morning,” he said. “Her mother left her there on the beach to look for shells while she did her shopping at the market; when she came back, the filly had disappeared.” He sighed, leaning back against his desk. “We’re still searching, but because of the location and timing, this seems connected to the other cases. We might have to close off that area if this doesn’t stop… I don’t know how it keeps happening, and in broad daylight, too.”

“Hmm… that is strange,” Twilight said. “Maybe my brother or somepony else could take us down to the area and Dash and I can have a look around?”

“That sounds like an excellent idea,” said the mayor, nodding in agreement. “We can also get you a list of the missing ponies, along with all of the ponies we’ve talked to with relation with the cases.”

“That sounds great, thank you,” Twilight responded. “C’mon, everypony—let’s go.”

As they turned tail and started walking away, the mayor spoke. “Hold on a second; I’d like to speak to Ms. Sparkle by herself.”

“Sure thing, Mayor Wit,” responded Shining Armor, who looked towards Rainbow and gestured towards the exit. As the pegasus flew out of the room, Shining followed and closed the doors behind them. Twilight stood in front of the desk, watching the mayor pace back and forth.

“Twilight…” he started. “I, that is… Ms. Sparkle… erm…” He paused, to compose himself. “I apologise; my nerves seem to have gotten the best of me. What I’m trying to say is this: it is very important to me—and the city of course, and these ponies—that you resolve this case as soon as possible.” When Twilight didn’t answer, he went on. “I just want to make sure that this goes smoothly… eheh… you know, this city, this great city… we’ve got a reputation to maintain.” He waved his hoof upwards, at the City of the Year certificates. “And I, well, I’m pretty new at being mayor. I just, um… I just don’t want my career to be marked, to be remembered by… erm… well, you know. This, uh, this incident.” He procured a hoofkerchief from a desk drawer and wiped a bead of sweat from his brow with his hoof.

“Well, erm… Mr. Mayor… I appreciate your concern—I really do,” Twilight began. “I’m sure that if I were in your position, I’d be pretty concerned for the reputation of Manehattan and even myself, especially if I thought I was the best pony for the job.” She paused. “And I will really do my very hardest to try and find these ponies, because that’s what I came here to do.”

The mayor exhaled in relief. “Oh, Twilight, I can’t thank you enou—”

“I’m not finished,” Twilight interrupted. Mayor Wit blinked. “I do fully intend to put all of my efforts into finding these missing ponies. But don’t think for a second that I’m doing it for your reputation, or to help you politically.” The mayor blanched. “I’m doing this because I care about other ponies and I want them to be safe, happy, and able to live their lives. And I firmly believe that you, as the mayor of this city, should be doing your job for that reason as well. Thank you for your time, and your assistance.” She said this calmly and, upon finishing, turned around and walked away, opening the door in front of her.

“Erm, well, thank you, Ms. Sparkle.”

“Believe me, it’s no problem. No problem at all.”

It was noon by the time Twilight Sparkle, Rainbow Dash, and Shining Armor reached the cargo district of Manehattan. The three ponies walked along the boardwalk, hearing cries of gulls above them as the sun shone brightly in the cloudless sky overhead. A few ponies were milling about, but the area was mostly empty. To their left, there was a series of docks with a few boats moored on their posts. Only one, a large grey and white ship, was a cargo carrier; they could see a few ponies using a pulley system to lift crates into the belly of the ship.

“It’s over here, in this alley,” Shining Armor said, pointing his hoof over to an alley blocked off with police caution tape. It was a dull yellow, weathered by how long it had been there. Shining Armor magically lifted the tape, and the two mares followed him close behind.

As the site of a disappearance, it didn’t look like your average crime scene. Nothing was broken; there was no blood, nor bodies, nor any sign of a struggle.

Rainbow Dash hovered around, looking around at the walls of the adjacent buildings; Twilight turned to her brother. “So, who was it that disappeared here?”

“Her name was Seafoam Dove; she was twenty-two and a unicorn glassblower. She lived alone in an apartment on the other side of the city. Her parents both also live in Manehattan, as does a brother who works at the same glass shop. They have all been ruled out as suspects.”

“Well, naturally!” Twilight exclaimed. “They’re family, after all.”

“Twily, I know you’re used to taking down all different kinds of monsters. But the ponies here—thankfully only a small few, but still some of them—can be much more monstrous than any beast you’ve encountered. Being related by blood or by marriage won’t stop them, not for a minute. These relatives all had alibis and have expressed genuine concern, but we can’t always rule the family out straight away.”

Twilight Sparkle gulped. “I’m glad that our family at least can be counted on to not commit crimes against each other.”

Shining Armor smiled. “Me too.”

“Anyways… how do they know that this Seafoam Dove disappeared here? Why couldn’t it have been somewhere else?” Twilight asked.

“That’s a good question,” Shining Armor started. “The main reason is that she was seen, by one of the ponies in the house to the left, entering this alley. That pony looked away for a few moments and, when they looked back, she was gone. They didn’t think much of it, but they gave us that information after Seafoam’s family reported her missing.”

“But isn’t it possible that Seafoam could have just trotted away while that pony wasn’t looking? Do we even know that somepony else was involved?”

“Indeed, at first we weren’t sure. You’re right—she definitely could have just walked away and left the city, by herself. And we’re still considering that as a possibility. But after the other disappearances, the similarities… they’re uncanny. There’s no way they’re not connected. You’ll see for yourself, soon.”

“Hey, you two! Stop being eggheads or whatever and come over here!” Rainbow Dash waved, a ways down the alley. Twilight Sparkle and Shining Armor cantered quickly over to where Dash was hovering.

“Look at the wall here,” said Rainbow, pointing her hoof at a patch of wall which the building behind them cast in shadow. “See how there’s kinda, uh, a green splatter shape?”

Twilight leaned in to get a closer look and, sure enough, Rainbow was right. There was, indeed, a ‘green splatter shape’; to be more precise, it looked as if someone had thrown some sort of green gooey substance at the wall and then removed it, leaving behind that residue. “Do you think it has anything to do with the case? It’s probably been here for a long time. I mean, there’s plenty of other stains all over the alley, and probably in all of the other alleys too.”

“But don’t ya think it would be, like, good to play it safe? I have a weird feeling about this stain… it’s different than all the others, I swear. Can’t you, like, take a sample or something and have the egghead ponies analyse it back at the lab?”

“This isn’t CSI: Mareami, Dash. Lab work takes actual ponies’ time and effort, you know, and we would want to be sure of anything that we have them test so we’re sure we’re not just wasting their time,” Twilight said. Rainbow visibly deflated.

“Hey, Dash, don’t sweat it,” said Shining Armor, putting a hoof on the mare’s back. “Don’t get your hopes up, but maybe you’ll find something similar at the next site. Then we’ll do a lab test for sure.”

Rainbow Dash’s ears perked up again. “You think? Hey, yeah! It’s gotta be there, it’s just gotta! C’mon, everypony! To the next site!”

“You done here, Twi?” asked Shining Armor.

“Yeah, I think I’ve seen all I need to see here for now. We can always come back if I need to see something else,” said Twilight.

“Woo!” shouted Rainbow Dash, gliding into the air and spiralling upwards. “Let’s go!”

Twilight Sparkle and Shining Armor had only walked but a few steps before they heard the same voice calling ahead of them.

“Wait, where are we going, exactly?”

“What did I tell ya?”

Rainbow Dash, to Twilight’s chagrin, had found a near-identical green stain on the wall the minute they arrived at the warehouse that had been the location of the second disappearance. A middle-aged married stallion named Sam Docks who managed the warehouse’s inventory was the pony who had vanished, seen just minutes before tallying crates of fruit. Again, it was very much possible that he had simply sneaked away from the city, but this seemed unlikely especially considering the similarity with the previous case.

“So, now that there’s another green splat here, will you get some for them to test in the lab?”

“Sure thing, Rainbow, but we’ll also have to go back to that alley and pick up a sample there too.”

Rainbow, hovering above the two ponies, simply laughed. “Ha! I’m double right! You totally should have gotten one there!”

Twilight rolled her eyes. She pulled a small glass vial from her saddlebag and magically extracted some of the liquid from the wall. The vial filled partway with translucent light green fluid. Once it was full enough, Twilight replaced the vial in her saddlebag and trotted over to join the others who were already leaving out through the large metal warehouse doors.

After they went back to the alley to get a sample of the first green liquid, Twilight Sparkle, Shining Armor, and Rainbow Dash continued on to the third location, a closed-off storefront which previously sold saltwater taffy, chocolates, and other various candies. The proprietor, a young mare named Sweetie Drops, had gone missing a week before, mere minutes after a customer left the shop. Even Rainbow Dash was starting to see that there was a pattern.

And, sure enough, on the wall behind the counter, in between the jars of taffy and chocolates, was a green splotch. Rainbow pumped her fist while Twilight rolled her eyes and collected a sample in another vial. Across the store, facing away from the two mares, Shining Armor had decided to sample a few of the chocolates from a jar on one of the shelves.

“Yo, Shiny, whatcha doin’ over there?” Rainbow asked, trying to peek her head around Shining Armor.

“Mmmmf—erm… hehe… nothing, nothing.” He quickly screwed the lid back on the jar and slid it onto the shelf.

Rainbow Dash raised an eyebrow at this, but said nothing. Wordless as well, Shining Armor hoofed a chocolate into Dash’s outstretched hoof, at which she smiled and immediately thrust the thing in her mouth.

A moment later, Twilight turned, appearing not to have noticed. “I think we’d better be off to the last one, now, shall we?”

The fourth and final place where a disappearance occurred was different in that it actually was on the beach rather than simply close to the ocean. Twilight Sparkle and Shining Armor walked along the shoreline, dry sand running through the cracks in their hooves and trapping itself in their fur coats; however, Rainbow Dash, hovering above, avoided the misery of granules in her wings.

Eventually, after passing a few families who were enjoying themselves in the mid-afternoon, the three reached a rock wall which led up to a steep cliff. It was the base of this cliff that the police barriers obstructed and therefore that was where they entered. The spot was itself unremarkable, but something else made it stand out from the others besides its location.

Rainbow’s head swivelled around in a chromatic blur. “You guys?”

“What?” said Shining Armor. Twilight looked up from the sand.

“I don’t see any of the green stuff here,” Rainbow said, squinting at the rock wall.

Twilight blinked. “Are you sure? Not anywhere? Remember, at the alley, it was kind of out of the way, kind of hard to spot.”

“Yeah, Twi, I’m pretty sure. I mean, where is there to hide it? It’s not on the wall anywhere, not even on the sand.”

“Hmm… I guess you’re right. Plus, this is out in broad daylight, whereas the other three were out of the way, in places where someone could go unseen. Hey, B.B.B.F.F., do you know about the witnesses for this case? Were there any?”

“No… the police department spoke with several ponies who attested to being on the beach in this area and they never saw a filly matching the description of Sunny Day,” Shining Armor replied. “I mean, it’s possible that she could have wandered off somewhere else. But the timing of the disappearance is what really seems to connect it.”

Twilight stood there for a moment, gazing out at the ocean. The sky was blue, and a few wafty clouds hung daintily here and there. The crashing of the waves beat into a steady rhythm—inhaling, exhaling, inhaling, exhaling—as she gathered her thoughts. At last, she spoke. “It’s possible that this one isn’t connected, but we also can’t rule it out just yet. Let’s just take what we have so far down to the police department so we can figure out what this green stuff is.”

“Sounds like a plan to me, sis.”

“Cool beans. Let’s get outta here—I don’t wanna get any beach cooties or else I won’t be able to fly.”

Shining Armor laughed. “Beach cooties aren’t a thing, you goof.”

“Or are they?” Rainbow offered in rebuttal, a sly grin plastered on her face.

“Uh, no,” said Twilight, beginning to walk away on the sand. “Cooties, beach or not, are just a primary school oversimplification of bacteria, and…”

“Goddess…” Rainbow exhaled, facehoofing. “What have I done?”

Despite Twilight’s objections, the lab’s identification of the green liquid only took about fifteen minutes. During that time, Shining Armor and Rainbow sat on a bench in the hall outside the laboratory while Twilight paced back and forth in front of them. When the forensic equinologist came back out into the hall, clipboard held magically in front of her, Twilight stopped and looked at her.

“So, what is it?” Rainbow asked.

“Kelp, Ms. Dash. This liquid is residue left by kelp, which was stuck to the surfaces and then removed shortly afterwards,” replied the mare.

“And it’s the same for the samples from all three surfaces?” Shining Armor asked.

“Yes, they all match up. What’s more interesting, though, is the variety of kelp. Due to its likely use as an adhesive, and based on the genetic material we’ve analysed thus far, it appears to be one of a few varieties of deep-sea kelp.”

Processing the information, Twilight looked up and blinked. “But… isn’t that pretty strange? How would deep-sea kelp end up on walls in Manehattan, near where ponies had disappeared? How could it even have gotten here?”

“There are a few different possibilities I can think of,” Shining Armor replied. “One explanation is that it could have been tracked on the hooves of somepony who came from one of the islands out east.”

“That’s possible,” said Twilight, “but I’m not sure how we could track them down. Have the disappearance sites been hoofprinted?”

“Yeah, but they don’t match anypony on file as far as I recall, and anyone who enters the city from the sea is hoofprinted. There was also something, uh, weird about the prints that they found, too… I can’t remember what it was, though, so we’d have to look into that.”

“Hmm, okay. I think we can scratch that one off the list for now, unless we can’t think of any other possibilities,” Twilight declared.

“Didn’t your brother say that he had a few other possibilities in mind, though?” asked Rainbow.

“I’m getting there, I’m getting there,” Shining Armor said. “If it’s not that, it could also be the symbol of a gang. Not one I’ve ever seen, but I’ve seen similar ones where a particular liquid is painted onto a building, in a certain shape. I dunno where they would’ve gotten the kelp, though. We could check the shipping records to see if anyone ordered any recently.”

“That sounds like a good idea…” Rainbow said. “Let’s do that next.”

“I agree—it might take a bit to get all of the records together from the shipping companies and search through them, but I’m sure it shouldn’t take us too long, especially with three or more of us.” Shining Armor paused. “The other possibility is that it was stolen from or taken by a pony in a research laboratory, like the one at Manehattan University. They have hundreds of students there with lab access, and any one of them could have done it.”

“If I may interrupt, Captain Armor?” the scientist interjected.

Shining shrugged. “Go right ahead.”

“With your permission, I can send this sample to a colleague at the university’s Marine Biology Lab and ask him to compare it with the samples they have there, to see if there’s a match.”

“That would be really helpful! Thank you so much.”

“Of course—I’m just doing my job.” With that, the mare walked off into the lab.

Once she had disappeared through the doors, Shining turned back to Rainbow and Twilight. “Let’s go start rounding up those shipping records,” he said. The two mares nodded in agreement, and all three walked together down the red-carpeted hall and out the large wooden double doors in the front of the building.