As part of my bid to write as much variety as possible, I bring you a horror story that Galaxina-the-Seedrian and I discussed briefly, aages ago. I hope it chills you to the core.

"Ferb is a hit man!"

Phineas's usual cheeriness turned into confusion. "What?"

"Ferb!" Isabella repeated urgently. "He's a hit man!"

It was not how Isabella usually entered the backyard. Phineas took a moment, studying Isabella's expression, and saw she was genuinely panicked. And she was. Isabella wasn't one to jump to conclusions, especially with an accusation as serious as murder, but the thought had occurred to her in a flash that very morning, and as much as she turned over the facts in her mind, they only confirmed it.

Phineas, however, was not so easily convinced.

"Isabella, I never thought I'd say this, but you've gone totally crazy."

"Hear me out," Isabella said, looking around nervously to make sure Ferb was not in the vicinity. She then produced the Daily Danville and pointed at the front page headline: 'French Ambassador Killed: Situation Described as Fishy'.

"He and Mayor Doofenshmirtz were visiting the Danville Aquarium when the glass to the shark tank broke and he was ripped to pieces by a great white!"

A shadow fell across Phineas's face. He studied the newspaper article intently for a moment. "Well... despite the delightful nautical play on words in the headline, the article suggests it was just an accident," Phineas said seriously.

"Maybe so," Isabella admitted. "But take a look at yesterday's paper!" She swapped that day's Danville Times that she was holding with the previous day's. "Look! 'Visiting British Dignitary Hit By Freak Lightning Strike… 27 Times'! And the day before that, 'Chocolate Factory Tour Turned Sour When German Ambassador Is Killed By Exploding Chocolate Bar'!"

"But Isabella, those were all described as accidents," Phineas said. "Albeit highly unfortunate ones for the people involved. And even if they weren't, there's no evidence Ferb was behind any of it!"

"Come on, Phineas. Who else would kill people like this? It's totally Ferb's style!"

"Nah, Ferb wouldn't hurt a fly," Phineas said. "Oh, unless it was some sort of evil bionic fly…"

"And you two have been doing more secret solo projects these days," Isabella continued, undeterred. "I'll bet his 'projects' have been assassinations! We need to get to the bottom of this!"

It really was a horrible accusation to make, and Isabella desperately wished it wasn't true. But it all lined up. What was that quote? When you have eliminated the impossible, whatever remains, however improbable, must be the truth. And it seemed to Isabella that there was only one improbable truth left. And as much as she loved him as a friend, Ferb did fit the bill, what with his shifty eyes and silent, secretive demeanour.

And if it was true, then that put her and Phineas in more danger with each passing second.

The red-headed inventor was silent, deep in thought for what felt to Isabella like an eternity. Then, finally, he nodded, in what seemed like acceptance. "Ok. Have you told anyone else about this yet?"

Isabella relaxed slightly, now that Phineas was on board. "No, just you." Ferb was his brother, so Isabella had decided that he deserved to hear her suspicions first. And if anyone could help her, it was Phineas.

"I see. Well, I need to see a man about some parts for one of those solo projects of mine," Phineas said, his expression brightening again as he made to leave the backyard. "But right after I get back, we'll get the gang together, perhaps sans Ferb, strange as it'll be, and get to the bottom of this."

"Oh, er, ok…" Isabella said. She then realised that Phineas was leaving her alone, possibly a stone's throw away from Ferb. "Oh, Phineas, er, mind if I come with you?"

"No!" he said, a little suddenly. "I mean, it's actually a surprise for you!" he scratched his neck anxiously. "And don't worry, even if Ferb was secretly evil, he wouldn't get you out in broad daylight in our backyard. That'd be way too boring!"

"I guess... where is he, anyway?"

"He's just inside. Relax, Isabella, Ferb's not a psychopathic murderer. Trust me," Phineas winked.

Isabella may have been more reassured by this had she not felt the gaze of a shadow from a bedroom window.

"Stay right here," Phineas instructed, and he then rushed out of the backyard, unusually quickly.

Realising her heart was racing and that there was nothing to worry about, Isabella slumped against the tree. Phineas was right: Ferb wouldn't get her here and now. Besides, she was a Fireside Troop leader. When she had her guard up, she could do anything. Phineas would get back and everyone would come together and they'd all get to the bottom of this.

And then Phineas will present his secret project, one just for me! She squealed inwardly. Could this be the day?

She allowed her mind to wander in the field of possible inventions and timelines. Would it be a romantic journey above the clouds? A statue of us, carved out of marble? A giant bouquet of flowers? Or perhaps he' s simply going to take my hand in his, stare lovingly at me with those great, wonderful eyes, click his fingers and whisk us away to have that Paris love scene that I've always wanted...

Isabella stirred with a groan, her eyes still closed. Her head throbbed painfully. The ground felt hard to the touch and the air smelled musty and damp, in stark contrast to the soft grass and fresh air of the backyard.

Strange, since Isabella didn't remember falling asleep at all, let alone in a place like this.

She concentrated on any memories that might explain how she got here, only her mind was blank past Phineas leaving her in the backyard. But her throbbing head suggested that despite Phineas's reasoning, Ferb must have done something after all, knocking her out and leaving her here.

But where was 'here'? She could hear the humming of some technology, adding evidence that Ferb had a hand in where she had ended up. She'd have to keep an eye out for him. Slowly, unaware and afraid of what she would see, her eyes opened... to meet an unexpected pure darkness.

It was at this moment she was tempted to scream and call out for help. But then she remembered she was Isabella Garcia-Shapiro, leader of Fireside Troop 46321, and now was not the time to panic. Instead, the Fireside Guide to Handling an Unfamiliar Situation appeared in her mind. Step 1 was to keep composed. She should not panic. Step 2 was to assess the situation properly.

Isabella realised she was curled up on the ground and carefully made to stand up. She could see a little into the darkness now, her eyes having adjusted. There seemed to be pickle jars filled with liquid of some sort on various pedestals around the room, translucent and eerie tubes connecting to and from them. She stared in bewilderment, turning to take in the rest of the room.

Then, suddenly, the lights flashed on, and she came face to face with a single human eye, looking right at her.

The grisly body part was floating in the jar, suspended in the unidentified liquid. Isabella gasped and staggered backwards. She crashed into another pedestal. A loud beep sounded and Isabella felt a liquid trickling down her back. The smell of iron filled her nose and she spun around sharply, fearing the worst of the fluid. Blood. It covered her back and shoes and was still spilling out from the tap she had triggered.

What is this?!

Desperately, she tried to escape the spreading pool of crimson on the floor. Backing away from it past the various pedestals, she could now see their macabre contents. A severed human hand. A person's nose. A foot. Hearts and livers, stomachs and intestines, all stored in jars like some mad scientist's trophy room.

Isabella felt sick to her stomach. She wished desperately for this all to be a dream, but the sticky blood on her clothes and hands and the ache in her back confirmed that this was all too real.

This must be one of Ferb's secret places, Isabella realised. She leaned on one of the pedestals, eyes shut, breathing hard to regain her composure. It took several minutes before she was able to keep her eyes open without wanting to throw up.

Ok, there must be some way out of here, right? she tried to convince herself. And I won't find it by waiting around… Slowly, she began walking through the lines of pedestals, looking for a door or exit.

She found a door, but she also found a desk, piles of papers with unintelligible markings stacked on top of it. There was also a nondescript notebook positioned unusually neatly in front of the desk chair. A compelling curiosity overcame her and she flipped open the notebook… and then immediately flipped it closed, upon seeing a coloured sketch of a disfigured person with body organs highlighted, shuffled around, annotated...

Ferb's researching zombies? The thought made Isabella shudder. Well, it certainly explained this room filled with body parts, though it wasn't an explanation that gave Isabella any relief.

Then the entire floor jolted.

Instinctively, Isabella grabbed onto the desk, as the room trembled. Though she could not see them, the tinkling glass and sloshing liquid created the vivid imagery of the suspended human organs squelching around in their jars around her. She tried to shut out the imagery and prayed for it to end. Then, as suddenly as it all began, it ended, with a large ding, as if she was in a mall elevator that had just reached the correct floor.

Isabella wasn't sure how much more she could take. Her heart was beating a thousand times a minute. All she knew was that Ferb couldn't, and wouldn't, let her escape, now that she knew what she did. But at this point, she just wanted this whole ordeal to be over. One way or another.

But she then heard a voice that was to change everything.

"Hey, Isabella!"

"Phineas?" she exclaimed, instinctively moving towards the sound of the voice. Relief washed over her; Phineas would save her. He would make this all go away.

"I take it the anaesthetic has worn off?"

Isabella realised the voice was coming from a speaker, and, looking up, spotted it in the corner of the room. A small microphone was below it and, judging from Phineas's response time and questioning, he could hear her too.

"Phineas, thank goodness you're here! Ferb dumped me into this horrible room filled with-"

"Woah there Isabella. I don't mean to cut you off, but if you tell me where you are, it'll spoil all the fun!"

"Wait, what?" Isabella asked, bewildered.

"And I already told you, Ferb's not responsible for any of this. He's just too nice!"

"But who else could it be?" she said exasperatedly. "All the murders were creative and meticulous, and Ferb is the most creative and meticulous person there is! Well, except..."

Isabella froze. Except the one other person who was at least as creative and meticulous as Ferb Fletcher.

"Ah, you've finally got it!"

Isabella turned slowly, in utter disbelief, towards the speaker. Phineas's voice hadn't changed in tone at all, but suddenly it sent icy cold shivers down Isabella's spine.

No… no, it can't be…

"Yup, it's me!"