Phineas makes quite the chilling psychopath, don't you agree?

It couldn't be Phineas. It just couldn't be.

"Wow Isabella, you sound just like Ferb right now! Because you're not actually saying anything yet I know exactly what you're thinking. But I'm afraid it's true. "

There it was again: that casual, easygoing voice that had gone from warm and inviting to chillingly disturbing in a single moment. A million questions flooded Isabella's mind, but she couldn't articulate any of them.

"I had better explain what's going on. You see, someone hired me online to destroy Mayor Doofenshmirtz's career without being detected, and I thought it was a great opportunity. I mean, just think of all the creative possibilities there are of diminishing someone's reputation!"

"So you settled on assassinating visiting dignitaries?" Isabella asked, already knowing the terrible answer.

"Yup! Without being detected, of course. But that's just part of the challenge!"

"Does… does Ferb know about this?"

"Well, he knows I'm doing something. And I know he's doing something too, but it's a secret. I'd tell you, but then I'd have to kill you… hehehe, 'kill you'. I mean, I have to anyway, but I'd better not tell you what Ferb's secret is. A promise is a promise, after all."

Isabella could almost imagine him wiping a tear from his eye as he chuckled at the joke he'd just thought of. She felt like laughing too, like a madwoman, at the sheer skew of Phineas's morals, that he was above breaking a promise to his other childhood friend just as he was about to kill her. The entire thing was utterly crazy.

"I mean, it's nothing personal, Isabella, but I can't have people knowing about what I do. That'd compromise the entire mission. But don't worry, I came up with a way that makes it fun!"

"Phineas, I can't think of a single way that killing me could possibly be fun!" Isabella shrieked, in desperate hysterics. "I never thought I'd say this, but you've gone totally crazy!"

"Hear me out. See, we're currently in a building of my design. It's made out of rooms that are like blocks that can rearrange themselves and connect to each other in different ways. I had the building drop us both into random rooms, and my job is to find and disintegrate you with my particle blaster as soon as possible while you try to hide and the building shuffles us around! Pretty cool, huh?"

No, no it isn't!

Isabella wanted to break down and cry. How, how could she live side by side with someone for so long, knew inside out, and have such a crush on no less, and not realise he was capable of all this unspeakable madness?

And he was going to do more. Isabella had no doubt in her mind that Phineas would blast her when he got the chance. He was a monster, a smiling psychopath. She still didn't fully believe it, her very mind didn't want to accept it, it seemed horribly wrong, but even as she thought of those words they made a twisted kind of sense at the same time, these words that went completely at odds and also perfectly aligned with the profile of her smiling neighbour, who lived to be creative and seize the day. Whose motto in life was the belief that you can achieve anything if you put your mind to it.

Even murder.

She couldn't let him get away with it. She wouldn't let him get away with it. For the second time, she reminded herself that she was Isabella Garcia-Shapiro, and she was a fearless Fireside troop leader. Well, she was supposed to be fearless. Isabella became acutely aware of how much her knees were shaking. And the tears that had escaped her eyes when she hadn't noticed.

Numbly, she began moving towards the room's exit, gingerly avoiding as much of the blood on the ground as she could. Her mind was mostly blank, perhaps as a defense mechanism. Maybe she was moving because she subconsciously didn't like the idea of doing nothing while Phineas closed in on her. She laid a hand on the doorknob, but a small shuffling noise on the other side of the door made the hairs on the back of her neck stand on end.

Her mind then suddenly went into overdrive. What was that? Is it Phineas? She listened hard, pressing her ear against the door. Nothing. Did I imagine it? If she did, then she'd be one step closer to the exit, but if it was Phineas...

The danger paralysed her. The doorknob was loose to turn but now it might as well have been superglued in place as far as Isabella was concerned. There was no way she could turn it knowing Phineas may be on the other side.

"Wow, three rooms already and I've still not found you! Isn't this exciting?"

If Phineas really was in the other room, then surely she'd have heard his voice through the door, but Isabella only heard it through the speaker. Or perhaps the walls were better soundproofed than their appearance suggested? Either way, Phineas's words were a sharp reminder to Isabella that she was getting nowhere fast. Mustering all her courage, Isabella took a deep breath and, with one motion, turned the doorknob and pushed the door open.

Isabella braced herself for the worst as the door swung open. But apart from a foul, yet strangely familiar, odour, nothing hit her. And the room was pitch black. Her body relaxed slightly and Isabella was in no real position to counter that. She tried to remind her body that the darkness could still be hiding anything.

The lighting is motion-sensitive. she thought, without warning. She had no idea how her subconscious thought of it, but as she thought about it, she realised it made sense. It explained why the lights had suddenly turned on earlier, and why she hadn't seen any obvious light switches. Again, her body wanted to be reassured by this, as it meant that there was nothing in the room which was moving. Which meant no Phineas.

But as the room she was currently standing in had showed her, there could be any number of unspeakable unmoving horrors just waiting in the darkness. And it was also possible there was something in there, but it was not moving very quickly. Something had made the sound she had heard, after all. Isabella just hoped that it was a machine of some kind.

But there was only one way to find out for sure. Tentatively, Isabella reached a hand in, and waved it vigorously.

The light slowly flickered on. Isabella could make out the features of a large bookcase, with books scattered all across the floor. The intensity of the light reached its peak and there was a loud groan from the left hand corner of the room. Isabella spun around sharply. What she saw made her leap out of her skin.

Or rather, who she saw.

It was Buford. But not the usual pale-skinned bully she knew. This Buford wore his distinctive black skull shirt, but it was torn and dirty, and revealed molding, fungal arms. His face was horribly disfigured and long lines of stitches held together patches of his skin, in a Frankensteinian style. He groaned, recoiling from the bright light, and began staggering towards her with surprising speed, dragging a partly broken leg with him.

Isabella leapt back into the Jar Room and slammed the door shut. But it didn't close. She looked down to see Buford's stubby arm poking through the gap, his hand grasping at the air. Isabella felt his finger brush against her and she recoiled, slamming the door with even more force. Buford groaned in pain. But the door still wouldn't shut.

Then, as suddenly as before, the entire room shook under Isabella's feet. There was a huge mechanical lurching sound, and she felt everything accelerating to the left. She pushed her back against the door, digging in her feet, to prevent the force flinging her across the room. Then, as before, a loud ding indicated it had stopped.

Isabella placed a hand on her chest, her heart now beating a thousand times a second, and breathing at least as fast. She had to get her bearings again. As her mental state returned to normal, she realised that the door she was leaning against had shut fully. Buford must have been pulled away by the room shift.

She sunk to her knees. That incident had exhausted her mentally and was taking its toll physically. The difficulty it indicated in even moving through one room now loomed over her: if every room was going to be as traumatic as these two, then she was doomed to stay in this room for the rest of her life. Which would be until Phineas found her.

Well, she had lasted longer than Buford had. A horrible image arose in Isabella's mind, one of Phineas poring over Buford's corpse laid out on a mad scientist's operating table, like something out of a bad horror film, as the crazed red-headed inventor looked over his specimen with the same curiosity and fascination with which he regarded a new puzzle game. In her mind, Phineas then took a knife and, with all the precision of a master surgeon, sliced the skin apart to get a hold of the grisly insides, biting his lip in concentration, or perhaps with his tongue slightly out and an eye closed as he focused in his unique, irresistible style...

Isabella began sobbing. She hated that her mind was still crazy about Phineas. She hated that she could do nothing but sit, paralysed, wanting to cry out of despair and lost love. Why, why was her mind still fantasizing about being right beside him as he began the operation?

A creaking from the other side of the room interrupted her thoughts. She immediately recognised it as a door swinging open and her body instinctively made for cover without a sound, positioning herself behind one of the stands supporting the jars. It was a good position, one that if Phineas walked right through to the door she was just at, he would not see her.

Isabella realised with a start that there was no chance of Phineas doing that. The lights were on. That indicated to Phineas that she was in there, if they really were motion-sensitive. Even if they stayed on for a long time after detecting any motion, Phineas would deduce that she might be in that room, and look around thoroughly, surely finding her if he did so.

It wasn't reassuring, and Isabella could already hear slow, measured footsteps entering the room. But then she looked down and saw something that really made her heart sink.

Footprints. A trail of red footprints leading right to the spot she was crouching in now. They were hers, of course. Footprints left by her as she panicked, oblivious to the crimson blood clinging to her shoes and leaving traces of her path.

So this was how it ended. Killed, while cowering in fear, by her best friend and crush. No dream future with Phineas, with a house and children, which was all she had ever wanted. So much for the words she had held onto since early in the summer: "Aunt Isabella! That means I'm going to marry Phineas!"

And for some reason, the joking "or Ferb" addition swam into mind and stayed there for a few seconds.

The footsteps began inching closer, after having paused momentarily about a meter away. So Phineas had seen her footprints and was coming for her. She had resolved to go with a fight, where there was a slim chance she could knock Phineas's weapon out of his hands and overpower him. But she couldn't stop shivering at the thought of the much more likely outcome.

The footsteps reached her.

With all the adrenaline she could muster, she leapt at her attacker, knocking him to the ground, throwing punches and kicks blindly, one of which connected clean on his cheek. He recoiled. She raised a fist, to hit him squarely in his large flat nose.

Flat nose… Ferb?!

She looked down in disbelief. She was indeed standing over Ferb, who had raised his arms protectively. She was breathing heavily again, and Ferb was looking at her with terror in his eyes. Well, no wonder. She imagined the scene from Ferb's point of view: that in a flash, his crazed, blood-covered friend began relentlessly attacking him, likely with a maniacal look in her eyes. Isabella backed down, and Ferb slowly rose to his feet, still a little wary of her. He was clutching a ray gun of some sort.

"Ferb," Isabella began. "What are you doing-" but Ferb signalled her to be quiet and pointed at the microphone in the corner of the room.

Ferb slowly got over the shock, and his expression changed to one of sadness and pity. He had come to rescue her, Isabella realised. She had accused him of murder, and now had viciously attacked him, but he was still going to go against his step-brother, his other half, to save her. Because he was Ferb. Tears welled up in her eyes as her body accepted the ordeal was over, and she finally succumbed to it, sinking to her knees as Ferb rushed to comfort her in a warm embrace.

Ferb would save her. Ferb would make this all go away.

But through her vision blurred by tears, a figure appeared in the doorway of the other side of the room. Ferb too spun around, to see his step-brother in the doorway.

Phineas grinned. "Found ya!"