Case Closed

With a final pat on Shetlock’s head, Unit One carefully rolled off the bed and let the sleeping stallion continue to slumber.

She had what she needed, and once again it was back to the mission. There was, however, one thing left to do.

Spotting the quill and parchment sitting neatly on the small desk, an idea entered her mind. A short letter to explain her absence when Shetlock woke up would divert any trace of suspicion, and in addition she felt that she owed him some explanation.

Well, it was mostly going to consist of lies, but it was the thought that counted.

Finishing her short note, having already learnt the Equine written language thanks to her time observing their society, she folded the parchment up and trotted to the door.

“Sweet dreams,” she farewelled softly, opening the door to their room and leaving. Closing it without a sound, she silently made her way down the narrow hallway and wooden staircase. Not a soul was awake in the inn, a positive boon. Reaching the heavy front door, she was surprised to find that there was no latch or lock to secure it against outside intrusion.

With a shake of her head at the overly trusting ponies, she exited into the cool night air. The windows of the surrounding shops and houses were dark, the only illumination coming from the large tree in the middle of the town. Making a note to avoid the hive of activity, she instead crept down the alley beside the inn.

Passing trashcans in the surprisingly clean alley, she silently cursed the seemingly constantly full-moon. It lit up the area more effectively than a streetlight, and was a huge hindrance to a stealthy night getaway. Still, she didn’t have much time, it would take her a fair number of hours to make it to her target and she still had one final thing to take care of.

Manoeuvring from alley to alley, she slowly made her way back to her trusty hidey place. Upon reaching the basement window, she slipped inside and headed towards a cluttered and dusty workbench.

“Would it kill him to clean down here?” she muttered, thinking of the eccentric stallion that owned the store. “Then again,” she continued, pulling out a single metal case as long and wide as her foreleg. “He’d probably wouldn’t be too happy with all of the stuff that I’ve got.” Along with the case was a single metal box, a solid blue light on the top next to a keypad. Opening the front, she stashed her remaining stun grenade. Trotting over to a tool chest, she retrieved probably the more important item to be sent back.

A stack of parchment containing a hastily written report, travel guides, books of the equine language and maps of the towns and cities followed the grenade, Unit One closing the door and locking it tight. Then, after entering in the required data and codes, she activated the device and stepped back.

A short, three second burst of blue light flashed before the box faded away, the container safely returned to base for the scientists to go nuts over. Honestly, she herself couldn’t see in value in this world, it wasn’t like the equines or other primitive races posed any threat. Still, orders were orders, and with it done there was only one thing left to do.

“Next stop, Canterlot,” she grinned, hefting the metal case onto her back and heading towards the window.

Hopefully, she’d soon be finished with this relatively boring assignment.

“Oh Baby I be just waiting for you, waiting for you. Waiting for you to enter my hearttt again.”

Singing to herself softly, Unit One glanced around to make sure there were no flying ponies checking the castle rooftops. She’d seen more of the bat-ponies, but they all were content to watch the city gate and patrol the walls. They hadn’t even questioned her entry at such a late time, not even raising an eye at her cover of being a travelling business-pony held up by bad weather.

“I’ve got a present for you, a present for you. Oh Baby I’ve got a present for youuu right here.”

She once again checked the scope on the disposable railgun she had set up in her rooftop hidey-hole, the grey barrel pointed right at the castle gate. Unofficially called the ‘One-shot Show Stopper’ by those in her line of work, the two-piece compact weapon carried a single round of high-density metal. It was designed to be easy to conceal, easy to assemble, easy to use, and most importantly it came with an inbuilt self-destruct after use.

Peering through the small sight, she zoomed it in right on the entrance.

Shifting on the roof tiles she had torn up and repurposed as a seat, she continued to amuse herself while she waited in the small hole in the highest tower spire.

“Do-do, do-ba-do. Do-do, be-bah-do.”

Idly testing the trigger with her hoof, she was thankful the weapon was designed for armored fingers. She found her pony form to be amusing, and couldn’t wait to try it out once back at base once she was done. Having to form a finger would have been of little effort, but this way was just somehow more fun.

Sweeping the area for any signs of movement, she caught a glimpse of shapes in the sky. Removing her eye from the scope, she looked up at the full moon. Soaring through the sky, the shapes turned out to be two pegasi-pulled chariots. She continued to track them, all the way up until they landed just inside of the castle gates.

“Showtime,” she mumbled, peering back through the scope while scores of bat-ponies from all over moved to intercept the chariots. As the armoured pegasi detached themselves or left the chariot, they were set upon by a group of bat-pony guards who had streamed out of the castle. There was a furious exchange of words, before the bat-ponies swarmed over the chariots to check every nook and cranny.

Unit One watched and waited, until finally her targets left their transports and stood amongst the guards. She identified the pony Major and even Shetlock himself among them, her smile widening at his presence.

Placing her sights over Aries’ head, she watched him glance around nervously. Deciding against shooting him there and then, she gave him a few more minutes of life and shifted targets. Moving onto the women and the dark-skinned man respectively, she noticed the way Simon talked with a bat-pony guard as if he had the situation under control. He was calm, far too calm for her liking.

The guards of both types surrounded the humans in a square formation, swords and spears drawn while poised for action. Slowly they moved towards the castle entrance, Unit One deciding it was time to strike.

“Cause every time you leave…” the crosshairs lowered, focusing on the middle of Simon’s chest. The safety was flicked off, the rifle already charged and primed. “My heart begins to bleed.”

As she pulled the trigger, many things happened at once. The most noticeable was when Simon glanced up towards where she was, or rather the general area. His arms moved protectively around the briefcase, cradling it at his side. There was movement through the scope as an unintelligible shout rang out, ponies scattering while the two other humans dived to the ground.

It was too late for Simon however, a muffled crack signalling the railgun’s round breaking through the sound barrier on its way towards its target.

Unit One only watched long enough to see the massive hole punched in Simon’s chest, the human falling back with about eight kilograms of weight removed from his body mass.

It was a certain kill.

Leaving the already melting railgun to finish its destruction cycle, she immediately bounded out of the hole in the roof and climbed down the other side. It was an observatory, the wide gap in the dome making it simple to slip in. Her hooves made dull thuds when she landed on a star-speckled blue rug, and she immediately weaved her way through the piles of books to leave the room.

Given her knowledge of defensive fortifications, she assumed that the castle had a likely war-room or safe-room down in the sublevels, or failing that a dungeon or vault. During an attack it would be logical to take any VIPs down below to safety, so she focused on finding a way down.

Moving quickly along the deserted corridor, she glanced into each room with an open door while she galloped past. It was mostly bedrooms and studies, all deserted.

Then, success in the form of a large and ornate stairwell was found. Racing down the red carpet, she reached the bottom and stepped onto the floor of a massive entrance hall. Hearing the rapidly approaching commotion filtering in through the open main doors, she looked around for an entrance to the lower levels.

‘There,’ she thought, dashing to the small side-stairway leading down. She made it into the doorway just in time, Unit One looking back to see a tall white pony rush out with a squad of guards in golden armour. Descending the bare stone stairs, she emerged into a small kitchen. Judging from the small size and plainness compared to the rest of the castle, she assumed that it was for either servants or prisoners.

Not finding anything useful, she poked her head out of the open doorway. The plain corridor that greeted her sloped down to the right, and the noise of clattering metal was coming from the left.

‘We have a winner.’

Once again racing off down the right, she rounded three corners before reaching a section with a single door to the left with another corner at the end. She turned it just in time to see a spring-yellow mare in a maid uniform exit the room. The pony looked up at her with surprise in her purple eyes, Unit One aiming to solve two problems at once.

The pony opened her mouth to talk, but didn’t even have time to yell before she was tackled back into the room. Unit One pinned her down and shoved a hoof over the maid’s mouth, simultaneously shutting the door with a hind leg. Glancing around, she took note of the shelves of cleaning products and bedsheets before looking deep into the mare’s eyes.

Those same eyes widened in absolute terror when the hoof not in pony mouth morphed into a wickedly sharp double-blade. Already rapid and muffled pleas were spilling out of the maid’s mouth, the pony starting to struggle. Unit One leaned her head down, the maid going completely still.

“Shhh,” Unit One hushed into a furry ear. “Don’t worry little pony, I won’t kill you if you do exactly what I say, okay?”

The mare nodded, Unit One smiling warmly at her. “Great. Now, I’m going to take my hoof away. If you fight me, try to escape, or try to yell for help, then I’ll bury this blade into your soft little neck, understand?” The maid started to sob, Unit One shaking her head. “Don’t cry, if you do well then I won’t hurt you, promise.”

Another slow nod, Unit One waiting for the sound of the many galloping hooves to pass by the door. Once they had gone, she got up and let the maid stand up on all four hooves. The pony was still crying, but so far made no move to disobey her orders.

“Very good pony,” Unit One praised, before smiling sweetly. “Now, strip.”

Unit One finished slicing herself across the chest, getting the perfect amount of blood splashed across the uniform. The feather-duster she was holding in her mouth nearly fell out, but she chomped down harder to hold it. Glancing to the now unclothed mare sobbing in the corner of the room, she briefly considered eliminating the witness.

‘Eh,’ she internally shrugged. ‘It’s not like I’m going to be stealthy after this.’ Looking down at her bloodied uniform, it also raised the question of why she didn’t just form the disguise from the start over her now-pink fur. Turning to leave, she smiled while she kicked open the door and dashed out into the corridor. ‘This way’s more fun.’

Leaving the mare behind, she raced down the corridor and turned the corner. The change of clothes had been fast and simple, but she still had to find and catch her quarry. Speeding up, she rounded corner after corner of the same bare stone corridors.

‘Is this place just a giant corkscrew going down?’

Her ears perked up, able to hear armoured hoof-beats and shouts from behind her.

“It’s down this way!”

Speeding up, she assumed that the guards had found the maid. ‘Guess I should have killed her. Oh well.’

Switching her ears forwards, she could hear another group ahead of her. Turning two more corners, she came face-to-face with a corridor and staircase packed full of guards escorting the tall pony she pegged as Celestia and the surviving two humans. Oh, and Shetlock was there as well, but it was no time for introductions.

The guards parted to let her through, Celestia moving out to meet her with a face filled with concern. Her horn lit up with a golden glow, Unit One guessing that she was going to attempt to heal her ‘cut’.

“Princess,” she huffed out, dropping her feather duster to the ground to speak. “Something attacked me in the last corridor; the monster is on its way after me!”

The guards rushed to where she had come from, pointing their spears out in preparation for an attack. They pushed her back as they placed themselves between her and the ‘danger’, with Celestia, Shetlock, and the humans also funneled to the rear of the armed group. The eight unicorns in the group of thirty guards powered their horns, small shields flickering into life to form a protective bubble over them.
Unfortunately for them, she was already inside.

A massive uproar of shouting rose up when her pursuers rounded the corner only to skid to a halt. Both groups of guards stared at each other, questions being asked by all of the ponies before one guard from the newly-arrived group yelled out in frustration and confusion.

“It was right here, we were right on its tail!”

“What do you mean? We’re waiting for it now!” a guard in front of her asked back, glancing around the room.

While the ponies were busy figuring out what had just happened, Unit One had been slowly making her way to an optimum spot. Smiling, she positioned herself behind the humans, before noticing Shetlock begin to turn towards her.

It was time to act.

“Oh, I also have a message for you, Harriet Snyder and Aries Brinstone. Was it all worth it?”

Her voice was heard over the guards, everyone whirling around to face her. Unfortunately for them it was too late, Unit One standing up on both legs in front of the woman. The human’s eyes grew wider, her hand shaking while she made to raise her gun.

‘Nice try.’

Like a striking snake her right foreleg smacked into tit, a spike forcing itself through the skin and fat to sink deep into the chest. Being able to literally feel the pierced heart cease beating, she withdrew the hoof and spike before landing back on all four hooves.

The dead woman swayed on the spot for a few moments before toppling over, dead eyes open wide while blood flowed from her chest wound. All of the ponies were too shocked to move, however the last target scrambled back in an attempt to put as many guards between her and him as possible. Unit One smirked at how, even in his panic, he still clutched their oh-so-important briefcase tight.

Celestia was the first pony to react, leaping in front of Aries with a shout. “Monster!” Unit One could hear the sadness and anger in her tone, Celestia’s glare accompanied by moist tears. The Princess spread her wings like a shield, forming a barrier in front of Aries. Her long horn was lowered, beginning to glow.

Unit One doubted it was a healing spell this time.

The guards were sparked into movement at the actions of their ruler, Unit One finding a wall of swords and spear points barricading Aries from her.

“A pony!?” the guard she recognised as Captain Bastion questioned.

She maintained her smile, planning to have some more fun. Making her optics flash the evilest shade of red she could pick, she let out a small giggle. “Well, not quite.”

Making her transformation as flashy as she could spare the energy for, she once again rearranged her outer layer. Pink fur turned back to her original pony colour, and once again Mellow was standing with a smile as the glow faded.

“...Mellow?” Unit One resisted the urge to wave happily at Shetlock.

“Actually Shetlock,” she replied with a widening smile. “My correct name is Unit One, and the ISA sends its regards.”

Shetlock was frozen on his hooves, unable to say anything else as the full weight of the situation hit him. He tried to convince himself that it wasn’t Mellow, the sweet mare who’d he’d spent a night with. It was a shape-shifting monstrosity, similar to the changelings that had invaded Canterlot a year ago.

But, as hard as he tried to justify the creature’s ability to look like Mellow, the evidence added up. At almost every crime scene she had been there, he’d even told her where he was going and…

“Oh, Celestia…” he whispered, despite the actual Princess being right next to him. “I… I told you what where we were going…”

Mellow, or ‘Unit One’ now, smiled apologetically. “Well, not exactly Shetlock. Don’t feel bad, it’s one of the functions I was created for after all. It was a case of the right time at the right place for me.”

“What are you?” Celestia questioned, teeth gritted.

Surprisingly, it was Aries who answered. “I-ISA drone. It ca- can shapeshift.” The human got even more frantic. “Stay back! It’ll- it’ll kill you- you all without a thought!”

A snort came from Unit One, the thing seeming completely unintimidated by either the guards or Celestia. “Drone? I’m an artificial intelligence, thank you very much.” She narrowed her eyes at Aries. “You shouldn’t even know what I am, traitor. Then again, former Researcher Brimstone, you would have probably been promoted to my creators’ section if you hadn’t gone and joined a group of rebels.”

Aries didn’t reply with words, only taking a sharp intake of breath.

“I can’t allow you to hurt him,” Celestia took over, taking a step forwards. Shetlock stepped back despite his shock, the power radiating from Celestia starting to manifest as a glow. “You will pay for the death you’ve caused, for the suffering. No matter what you are, I will not let you harm another being.”

“Why are you defending them?” Unit One huffed. “They are the criminals after all. I’m merely doing my job.”

Celestia’s eyes narrowed further. “Anything that murders others in cold blood, and enjoys it, is too dangerous to let roam free. Normally I’d banish you to Tartarus for the safety of all, but…” her gaze turned to the dead body of Harriet and back. “You’ve already caused far too much damage that I cannot risk you getting free.”

Unit One’s tail flicked with irritation, Shetlock not noticing the unusually pony-like gesture as his mouth opened and closed repeatedly.

“I can’t help it if I’m programmed to enjoy my work,” Unit One fired back. She glared at Celestia with a frown. “You don’t know what you’re interfering with, none of you do.”

“You’ll n-never get thi-this!” Shetlock looked back at Aries, the human hugging the briefcase to his chest. “I’ll end all of- of the UIP’s evil!”

Probably the last thing everyone was expecting was for the sudden bout of laughter to rise from Unit One. It was filled with complete mirth, the pony-lookalike shaking her head before grinning at Aries.

“’Never get it’? ‘End all of the UIP’s evil’? What, you think some subspace teleporter blueprints is going to help your almost non-existent rebellion destroy an entire empire? For a scientist you’re pretty stupid.” Taking a second to brush her mane back with a hoof, Unit One continued on nonchalantly. “Besides, you remember that technician that you gave the case to program in that lock code? Guess who was working for us.”

Aries’ eyes nearly grew as wide as dinner plates. “N-n-no…”

“Oh yes,” Unit One shrugged. “Funny how the promise of immunity and a wad of money can convince people to give up their ideals of revolt.
All he did was take out the plans, replace them with blank paper…” she paused, raising a hoof to her chin. “Oh yeah, and slipped in that tracking device for us. He was such a nice man. I hear he bought a bakery with some of the money, you know.”

A clang rang out as the briefcase hit the stone floor, Aries staring at his hands as if they were covered with blood. “That means…”

“Yep,” Unit One grinned. “All of those bases and safe houses? You and your friends led us to every, single, one. It was so easy, ad you and your dim-witted traitor friends didn’t expect a thing.” While Aries shuddered, she nodded to herself. “It was totally worth saving you for last, the look on your face is priceless.”

Aries started to openly sob, Shetlock boing pushed back while Celestia advanced on Unit One once more with horn charged.

“Enough, you are obviously a creature of darkness, whatever you are. Of all the foes I have faced, none have driven me to such pure hatred.”

Shetlock hid behind a shaking guard, Unit One crouching low with her tongue flicking over her lips. Her back glowed, three pairs of holes large enough to stick a hoof in appearing in the fur. Shetlock could see the dark metal insides from his spot, revulsion turning his stomach.
“If I have to go through, that’s fine,” she told Celestia. “I was asked to avoid killing you ponies, you know. Something about keeping the chance of future dealings open.”

“I will never cooperate to you or your dark masters, not while I draw breath.”

Unit One smirked. “Suit yourself. I guess all that’s left to do is to fill this corridor, you, your guards, Aries, and unfortunately even Shetlock with explosions and shrapnel.” The holes in her back seemed to twitch, Celestia’s face hardening at the threat.

“I… I can’t let it happen.”

All except Celestia turned to face Aries, the human’s speech the clearest he had spoken so far. Shetlock’s eyes widened when he saw the gun in Aries’ hand.

The barrel was pointed up against the humans chin.

“Aries, don’t…” Shetlock began, his professionalism breaking through his shook while he raised a calming hoof. “Relax, Celestia can protect you and-“

“No!” Aries shouted, causing them all to wince. Celestia began to glance back, the human glaring at Unit One. “I won’t let any of these ponies to get hurt, I just want it all to s-stop!” He closed his eyes, Celestia’s horn dying out as she reached out with a wing to stop him.

“Aries, n-!”

She was cut off by the gun discharging.

The guards at the back were spattered with specks of blood, the stone ceiling about Aries coping the most of his blood and brains. The smell of gunpowder mixed with copper filled the air, the bang of the gunshot ringing in every ear.

Aries collapsed forwards, Celestia vainly reaching out her wings to catch his falling body. She held his chest to her neck, but with the back of his head gone there was no chance of saving him. Shetlock watched while, for the first time for years, Celestia wept openly. No-one moved, even the guards unable to act with their eyes locked on their sobbing ruler.

“Huh,” Unit One broke the silence as she stood up and the holes in her back disappeared. “That sure made it eas-“

Celestia whipped her head around, horn and eyes glowing. “Murderer!”

A golden wave of magic fired out of the horn, engulfing Unit One and the stairwell behind her with burning light. Shetlock had to turn away, the blast so strong it was like the unrestrained radiance of the sun. He could feel the heat and smell his mane burning, his hat flying off to land behind them somewhere.

All of a sudden, the blinding light died out and cut off. Blinking to clear the spots from his vision, Shetlock turned back to see what was left. The guards were likewise recovering, spears and swords lying on the floor where they had been dropped. Celestia was still cradling Aries’ body, her face locked in a stone cold stare. The stone walls and floor of the stairwell were glowing red and warped, almost like they had melted.

Looking to where Unit One had been standing, Shetlock could see only four tan hooves, steam rising from where the fetlocks, legs, and everything else up had been completely obliterated. While they watched, the hooves crumbled into dust and disappeared, leaving zero trace of the murderous machine.

Unit One, also known as Mellow, was dead.

“Is… is it over?”

No one answered the guard, Shetlock sitting down on the dropped briefcase while patting out his smoldering mane.

‘Case solved,’ was his last thought, right before he fell backwards and finally passed out from the sheer shock.

Sweet Treats ambled over towards the bar, a smile on her face and a drink in her purple magic field. Her target was the vested earth pony stallion sitting alone, nursing what appeared to be a strong whiskey. His tie and the hat on the bar wasn’t unusual for a Manehattan drinking establishment, and he was rather cute.

Briefly making sure that her cherry-red mane was neat and her white coat was in order, Sweet Treats approached and climbed up onto the stool beside him. Taking a sip of her drink, she placed a foreleg on the bar and gave him a smile. “Hi there, you look a little down.”

He turned to look at her, the tired eyes not harming his looks as much as would be expected. Giving him a glance over, she noticed the badge on his vest.

‘Chief Detective Shetlock,’ she thought with a swish of her tail. ‘Oh, a police officer, this night might be better than expected!’

“What?”

The blunt question caught her off guard, Sweet Treats however quickly recovered and gave him a disarming smile.

“I was just worried about you,” she said, the stallion glancing down while she put a forehoof over his. “Such a cute stallion shouldn’t be looking so sad.”

Her hoof was not so much brushed but rather thrown off, the stallion finishing his drink with a gulp and putting on his hat before leaving his seat. “Sorry,” he apologised without looking at her. “But I don’t go with mares in bars anymore.”

Sweet Treats stared in shock as he trotted out without another word or further explanation. Turning to the barkeep, she noticed the blue pegasus stallion looked just as surprised as she was.

“Was it something I said?”

In a subterranean corridor underneath Canterlot castle, a single speck of blue light flashed briefly in the darkness.

In the corner, by a boarded up door with a dead rat beside it, another blue glow lit up the blackness for a moment.

A single, furless pony hoof twitched, and another stray nanobot came back online and added its tiny mass to the reforming shape.

And then, another.

And... another.

The End… for now.

Author's Note

Unit One is kill... or is she?

That's right, the end of this fic and, as per the norm for me it seems, the path for a sequel.
How soon? I don't really know right now, but...

You can bet your left nipple Shetlock won't take it very well.

Until next time.