Pinkie Pie sank to her knees in despair as she took in the gruesome view in front of her, breaking down into tears.

"I'm so sorry, Pinkie... we couldn't save her in time." Princess Twilight Sparkle hung her head, having also been majorly effected by Rarity's sudden death. In fact, she had even neglected to do the royal duties required of her for the day and instead rushed to the Carousel Boutique as soon as word had reached her ears.

"How exactly did this happen? Tell me, how exactly did this happen?" Rainbow Dash's voice rose higher and higher as she rounded on Sweetie Belle, her eyes blazing with rage.

"I-I don't k-know," Sweetie Belle stammered, terror evident on her face, "I j-just came up here after R-Rarity didn't answer me and I s-saw her like t-this."

"Calm down now, ya'll. Cryin' will get ya nowhere; it's best to actually do somethin' about this and find out who murdered Rarity in cold blood. Ya with me, gals?" Applejack cut into the others' devastated grieving, her tone firm.

"Y-Yes," Fluttershy whispered, her eyes glittering with crystal tears, "I-I just don't get why s-somepony would do something so h-horrible."

Reluctantly, the others followed in her lead, finally accepting the truth. They owed it to Rarity to at least figure out her murderer if not having saved her in time... besides, justice needed to be served properly, and the remaining friends weren't going to neglect the opportunity to do so.

"We first need to investigate the crime scene," Twilight finally spoke, her choked voice piercing the eerie silence that had just begun to dominate the room. "Judging by the body, Rarity must have only been dead for at least an hour or so. Sweetie Belle, do you remember the last pony to enter the Boutique during this time?"

Sweetie Belle's expression converted to that of thoughtfulness as she tried to relieve some of her previous memories. "We got like ten visitors at the same time an hour ago; it was the most visitors we've ever achieved today. Rarity was still alive back then before she went upstairs to work on a brand new line. I'm pretty sure that when she did, though, that everypony had already left."

Rainbow Dash snorted quite rudely. "Well, now we have a basic picture of what the Boutique was like an hour ago. Gotta say though, it wasn't really that helpful, especially in trying to figure out who this darned killer is."

"Where... where did you go when Rarity went upstairs?" Fluttershy squeaked, her voice so quiet that the others barely just heard her.

"Oh, about that," Sweetie Belle paused for a brief moment before she continued, "I went to the downstairs storage room to check out some fabrics so I could try to be helpful, but when I was done and called Rarity's name a few times, she didn't respond; I think she was murdered during that time."

It was then that a self-satisfied shout from Rainbow Dash caught their attention, directing their gazes to the rainbow-maned pegasus. She was standing by the bed on which Rarity's body lay upon, uncovering a discarded object that had just been hidden underneath their friend's blood-splattered blanket. "It's a knife with some kind of green substance on it," Rainbow announced, clearly proud of herself for having discovered the knife. "I'm certain this was the murder weapon that the killer used on Rarity. The substance's probably some sort of poison too, because the messy bed here shows that Rarity struggled for a bit before dying. There's also stab wounds on her that are near her vital organs."

Applejack whistled. "Wow there, Rainbow. Ah never knew ya were such a good detective."

Rainbow Dash, upon hearing the farmpony's words, immediately swelled with pride. "Not everyone can be as awesome as me, you know."

"The window's open," Twilight suddenly remarked, her expression one of intense alarm, "which means that only a pegasus could have done this."

"Well, yeah, 'cause pegasi can fly darn well. It doesn't mean that a unicorn didn't do this, though, Twi. They could have just used that magic of theirs to levitate themselves to Rarity's window," Applejack told her.

"Applejack, a unicorn would have needed to exhaust a lot of strength in order to use levitation from the ground. Rarity's room isn't exactly on the first floor, you know," Twilight countered, immediately denying Applejack's far-fetched theory.

Applejack - her pride slightly wounded from Twilight's words as she believed that the alicorn was insulting her intelligence - opened her mouth to speak, but was interrupted as a familiar, yet malice-filled voice, sounded from behind them.

"It doesn't matter if it's a unicorn or not," Pinkie Pie growled as she pushed herself to her hooves. Her mane had deflated completely from its usual poofy state and was now a darker pink, along with her body. "I'm going to make sure that whoever murdered Rarity... will regret it. Badly." She laughed darkly, a sadistic gleam to her eyes.

"Uh... Pinkie? Ya alright there?" Applejack gulped, clearly frightened at her friend's sudden change of demeanor.

"Why, of course I am!" Pinkie giggled madly as she turned around to leave, her hoof now sporting a silver knife that'd appeared out of nowhere.

Fluttershy was now trembling in terror, throwing anxious glances around the room. "Um, g-girls? I-I really don't l-like where this is g-going."

"Oh, for Celestia's sake! She's got a bucking knife, ponies! Why are we just standing here and not trying to stop her from doing something bad instead?" Rainbow Dash suddenly burst out, no longer able to contain the frustration boiling within her.

"M-Maybe because we're s-scared?" Fluttershy suggested meekly, only to receive an angry glare from the rainbow-maned pegasus in response. Immediately, she shrunk down, her terror having increased tenfold.

"Ya've gotta admit, though, that Rainbow does have a point," Applejack said, her voice awfully quieter than normal. "For all Ah know, Pinkie's gone insane with despair an' there's a murderer - no, maybe two now that Pinkie's like that - on the loose. She won't stop in her quest for blood until she's avenged Rarity."

Twilight sighed deeply. "That's not the point, Applejack. The point is that as the one of the Elements of Harmony, murdering somepony else in cold blood is the one thing that Harmony absolutely forbids, which means that after she's gotten her revenge... she'll no longer be the Element of Laughter that we know and love."

A sharp intake of breath on Fluttershy's part didn't do anything to improve their now dampened moods.

"Why didn't you tell us earlier, Twilight? We've gotta stop Pinkie before she actually kills somepony! C'mon, girls, let's go!" Driven by her utter determination, Rainbow Dash zoomed out of the room through the open window and into Ponyville, where she then cast a desperate eye for a pink - actually, dark pink - mare.

Back at the Carousel Boutique, Applejack was about to charge out of Rarity's room when she realized that the others were still exchanging anxious glances. "Aren't ya'll comin'? This isn't yer normal thing that happens every day, y'know! We've got two possible murderers on our hooves!"

"U-Um, do I h-have to g-go?" Fluttershy spoke up, only to receive a glare from Applejack.

The farmpony narrowed her eyes. "Don't tell me that even durin' a time like this, ya still can't get outta that shell of yers, Fluttershy! Pinkie's gone mad and Rarity's been buckin' killed! Do ya not care?"

"I-I d-don't k-know," Fluttershy swallowed, visibly trembling, "I-I'm just really s-scared."

"Yer either comin' or not, Fluttershy." Without another word, Applejack spun around and galloped out of sight, leaving Fluttershy and Twilight behind.

Twilight glanced sideways at the yellow pegasus. "I can't really help you on this, Fluttershy. You've got to learn to come out of your shell, and since there's important things at stake, I'm pretty sure it won't be quite difficult for you. Be strong for our friends." She too broke into a run as she exited Fluttershy's view.

"For my friends... I have to be strong... for them." Fluttershy gulped, staring after Twilight helplessly as she engaged in a mental battle with her very own personality.

Applejack cursed under her breath. She could no longer see Rainbow Dash from below, as the rainbow-maned pegasus had just suddenly disappeared for no reason whatsoever. Where the hay is she?

Soon after, a rainbow streak caught her eye as she once again raised her gaze to the sky, finally catching a glimpse of the friend she'd been searching for. "Rainbow!" she called as loudly as she could, waving a frantic hoof. To her relief, Rainbow Dash slowed down, having finally noticed her.

"Applejack?" she asked as she landed, folding her wings. "What are you doing out here?'

"Tryin' to find Pinkie as well, of course! What, ya thought that ya'd be alone in this?" Applejack responded matter-of-factly, tipping her Stetson slightly downward.

Rainbow Dash shrugged. "I haven't spotted her since she ran away from the Boutique. Not even a single hint of her anywhere, which is impossible."

"Let's try again then," Applejack suggested. "Ah'll help ya out with the searchin'. Ya with me?"

"I thought you'd never ask," Rainbow grinned, unfolding her wings and taking flight once again. "C'mon, then! We haven't got all day, you know!"

"Right behind ya, pardner!" Applejack took off after the rainbow-maned pegasus, filled with a newfound energy.

Pinkie Pie - or rather, Pinkamena Diane Pie - paused as she passed Sugarcube Corner, her past memories flashing before her as she witnessed scenes of her still being happy and hosting fun parties for other ponies, always bringing forth a smile upon their faces. I was so happy back then... what happened to me that made me this way?

However, as soon as she'd began pondering about what encouraged her transformation into her alter ego, Pinkamena seized control again as hatred and fury once again filled her. "Rarity must be avenged no matter the cost!" Pinkie growled, her now maniacal gaze darting all around her as she searched for her desired victim.

"Pinkie, don't ya dare move another hoof!" a familiar, heavily accented voice reached the deranged mare's ears as she whirled around to find Applejack standing there, panting heavily. The sound of wingbeats also attracted her attention as Rainbow Dash landed beside the farmpony, folding her wings. "We've finally gotcha, Pinkie!"

Pinkie narrowed her eyes, a demented grin forming on her face. If I can't find out who murdered Rarity... I'll murder everypony until somepony admits they're the culprit!

"Hey, Dashie!" she sang, her silver knife shining menacingly in the sun as she slowly advanced on the rainbow-maned pegasus. Rainbow Dash, realizing Pinkie's true intent, quickly screamed as she unfolded her wings and bolted to the sky. "Don't you wanna play? Aww, c'mon, don't run from your friend Pinkie Pie!"

"You're not my friend! You'll never be! I just want the old Pinkie Pie back!" Rainbow Dash shouted back, increasing her speed.

Pinkie, upon hearing her words, immediately faltered as her grip loosened on her knife and it clattered to the floor loudly. "You... want the old me back?" she whispered, her voice cracking.

"Eeyup," Applejack said in a perfect imitation of her brother, trotting into view. Pinkie recoiled in surprise; she'd forgotten that the farmpony was there. "Don't be like this, Pinkie. Just 'cause Rarity died doesn't mean sheddin' blood is the answer. We'll always honor Rarity's memory and the generous things she's done for us. Besides, Ah'm certain she's in a better place now, enjoyin' makin' pretty dresses of all kind and achievin' her fashion dreams."

Pinkie's eyes widened as a torrent of former memories rushed through her mind, all of them consisting of either her being happy or just hanging out with her friends. "A-Applejack, I-I..."

The real Pinkie struggled for control, but was only locked away helplessly in the end as Pinkamena easily gained victory over her. "No!" Pinkie-but-not-really-Pinkie snarled as she retrieved her knife, shocking Applejack to the core.

The dark pink mare, taking note of her reaction, immediately began to giggle madly. "Oh, your face was so hilarious, Applejack! Aren't you just glad to see me? How about playing a game with me? It'll be so fun!" She slowly made her way closer and closer to Applejack, her silver knife glinting.

"Oh, ponyfeathers," Applejack gulped, backing up anxiously. Rainbow Dash, on the other hoof, had finally realized that Pinkie was no longer chasing her and was instead heading for Applejack.

"Applejack! Hang on tight, I'm coming!" the rainbow-maned pegasus yelled, rushing to her friend's aid as fast as she could.

Author's Note

For those of you who are wondering why I don't refer to Pinkie as Pinkamena even though it's clear she's descended into madness:

It's still Pinkie. Pinkamena's hate and rage is basically influencing her, causing her to do things she would never have done before. I suppose you could say that while Pinkamena remains trapped in the deepest parts of Pinkie's mind, she's gathered enough strength to technically "take over her mind".

I hope this explanation can answer any questions you may have regarding this matter.