First things first, disclaimer: I don't own Phineas and Ferb, or any of it characters. I only own my OC's and the plot line. Credit to Dan Povenmire and Jeff "Swampy" Marsh. Rated T for violence and descriptive gore.

So I wrote this a while ago, but it was too early for Halloween, so I waited till now to submit it. The gang is 12, and everything's pretty much gone on the same. This is Halloween night. Enjoy!

Ding dong.

Phineas Flynn opened up the door with a bowl of candy in his hands, expecting another kid trick-or-treating. What he wasn't expecting was a familiar neighborhood girl whose black hair was twisted in all ways above her head, and whose dress was covered in hundreds of red sparkles. Isabella laughed and held out her bag.

"Trick-or-treat!" she said. Phineas laughed as well and let her inside.

"Does that mean I don't get any candy?" she asked, pretending to be sad. Phineas smiled and walked her into the kitchen, where there were all sorts of goodies laid out on the counters, from cookies to candy apples to giant chocolate balls.

"Wow, you guys really went all out," she remarked. Phineas held out a plate of chocolate cookies to her. She took one and took a bite.

"Mmmm, still warm," she said after swallowing. "Thanks."

"No problem," Phineas replied, taking one for himself and putting the plate back down. "They're for the party later. Candace finally got permission to host a Halloween party, and Ferb and I offered to make the snacks. Everyone should be arriving any time now."

"Well that explains all the decorations," she said, looking around. Lots of people decorate at Halloween, but the Flynn-Fletcher house was completely transformed. Very realistic skeletons were hanging all about, cob webs covered almost every surface, and orange and black tinsel hung from everywhere that it could. The entire house was amazing; inside and out. There must have been at least a hundred pumpkins throughout the entire property, all carved with the most intricate designs.

"Where is everyone?" Isabella asked, glancing around.

"Candace is upstairs with Stacy getting ready for the party," said Phineas, "my parents are out hosting a Halloween themed antique auction, and Ferb is waiting with everyone else at the mansion."

At the mention of the mansion, Isabella got very nervous.

"Is that where we're going?" she asked nervously. There was only one place that Phineas could be referring to. The old abandoned mansion atop Whilton Hill. There were rumours of kids disappearing when they snuck onto the property, and of strange noises coming from the house at night.

About a hundred years ago, an old couple had lived there, and then one day a mysterious fire had started and ruined the entire house. The couple was perfectly fine, and they had the house completely fixed, but then they vanished, leaving no heir to the property. After a vigorous investigation, for some strange reason, the house was left alone, declared private property. Or so they say. No one knows for sure what really happened to the house. Kids sneak into it sometimes, but whenever they do, they never come back. Isabella knew this, because about a year ago, a kid in their class, Tommy Canton, had told everyone that he was going to go into the house that night and find out what the big deal was.

He never showed up for school the next day. And then the police came, asking for any information anyone had about the missing boy. They told them Whilton Mansion. But he never turned up. The trail was left cold and Tommy was never found. No one talked about him much; it was a very touchy subject. The adults gave no information, scolding kids whenever they suggested it was because the house was haunted. But all the kids knew about the house. They had all heard the stories, and knew that they had to be true. No one dared go in to the house to look for Tommy; they were all too scared for their lives.

"Don't worry Isabella, there's nothing to be afraid of," soothed Phineas. But Isabella was not convinced.

"What about Tommy?"

Phineas' expression darkened. Tommy had been a good friend, and he always acted like that when the missing boy was brought up.

"I'm sorry Phineas," apologized Isabella. Phineas shook his head.

"Don't be. It was over a year ago." He forced a small smile onto his face.

"So why are we going to the Whilton Mansion?" she asked, taking the topic of the conversation off of Tommy.

"Well, we just want to see what's really there," he explained. "Everyone is always freaking out about it, and we want to find out the truth. Besides, there will be a bunch of us going in together."

Isabella bit her bottom lip nervously. Of course she loved adventure, but this was a bit much. It wasn't just some game this time, it could be dangerous. Phineas saw how nervous she was and took her hand, smiling at her.

"Don't worry," he said. "I'll be right there the whole time."

She blushed, and after a second she nodded.

"Alright, I'll go."

About twenty minutes later, Phineas and Isabella arrived just outside the mansion's property to find no one around.

"That's strange," said Phineas, looking around for their friends. "Ferb said they were going to wait for us here."

Suddenly, three dark shapes jumped out of the bushes and tackled Phineas to the ground. Isabella screamed, and then she found herself extremely annoyed to find Buford, Django, and Ferb, all holding Phineas down and laughing their heads off. Phineas let out a nervous laugh when he realized it was just his friends, but Isabella wasn't satisfied.

"That wasn't funny you guys!" she exclaimed, pushing them off Phineas and helping him to his feet. The three of them stood up, still laughing, and then Baljeet and Irving walked out from behind the bushes as well, shaking their heads.

"Let me just say that I was totally opposed to this," said Baljeet. Irving nodded his agreement.

"No big deal. So, are we ready to go in?" asked Phineas. Isabella took a moment to check out her friends outfits. None of them were trick-or-treating this year, but they were all in partial costumes, such as herself. Ferb had on a long red and black cape, with a high collar. Baljeet was wearing a lab coat and his hair was spiked upwards. Buford was simpler, in a leather jacket complete with chains hanging down from pockets. Django was dressed like an artist, such as he was, with paint splattered clothes and a set of brushes hanging from his belt. Irving was… dressed as Phineas (not creepy at all). Phineas was wearing a top hat and dress coat, and had skeleton gloves on his hands. Isabella was dressed in a knee length dark red dress with tons of sparkles, and her hair was twisted up high on her head.

"Yeah, I think so," answered Django. Everyone else nodded, so Ferb walked over to the old gate and pushed it open. It creaked loudly, and then hit the stone wall with a crash. Isabella winced at the sound, gazing over the mansion in fear.

It was four stories high, with a tall pointed tower coming out of the west wing. The entire property was huge, with dead trees all over. A short, crumbled stone wall surrounded the property, and the only opening was the rusty metal gate. It had a lock on it, but a bunch of kids had broken it a while ago, intending to sneak in, but they were busted by the police before they could. The house itself was impressive, although the sight of it scared Isabella stiff. The windows were mostly broken, and vines were creeping their way up the walls. The house was a faded grayish brown colour, but the paint was peeling off. A large front porch was house to a porch swing that was hanging low to one side, broken for years. Empty pots lie about as well, and an old rocking chair sat near the edge, one of its arm-rests missing. The wind blew around them, making the wind-chimes move slightly and make an eerie sound.

"I don't know about this you guys," said Isabella, feeling more scared now that they were actually there. "What if something bad happens?"

Buford mumbled something about girls, but Django punched him lightly in the shoulder to get him to be quiet. Usually, Isabella was the only girl there, so they all treated her with respect. She liked hanging out with only boys. After that summer when they built all those crazy inventions, she had stopped wearing as much pink, and lost her love of unicorns and rainbows and things like that. She got more into sports, sometimes being allowed to play on the boys teams because of her skill, which made her very popular among the other guys. Although she was still friends with her old Fireside Girls troop, she mostly hung out with the six she was now with.

"Trust me Isabella," said Phineas, taking her hand once again to reassure her. "There's nothing to be afraid of. We brought a flashlight, and we'll stay together the whole time. And if something does go wrong, we'll get the heck out of there."

Isabella took a deep breathe to calm herself down. She glanced at the old house once again, and then slowly nodded.

"Let's do it."

The seven of them approached the front porch. Buford, being as stubborn as he always was, was the first to step onto it, walking right up to the door. The rest of them came up more slowly, glancing around and checking things out. Phineas still held Isabella's hand, which helped her to stay calm in the situation. Buford stepped aside as Phineas walked up to the door, and carefully placed his other hand on the knob. He looked back to see Ferb holding the flashlight. His step-brother nodded, and so the young red-head took a deep breathe, and slowly turned his hand. The door opened, and he took the first step inside.

So, did you like the intro? This started as a one-shot, and then I kept getting ideas, and it turned into this! Okay, just a few things I'd like to say first.

One, there will be people getting killed. Of course I'm not going to tell you who, but I'm just warning you now, it's possible that your favourite character will die sometime. So please don't be too pissed off at me. Second, there is some Phinabella, but it's not the main focus of the story. That's the only pairing. Third, it's rated T for now, but I may need to change the rating later on to M, because of descriptive gore. If you think I should change it, just tell me, and I will. And fourth, because of the afore mentioned deaths, do not flame me when it happens, cause it will. If you don't like stories where people die, then leave now. Because you will be severely pissed at yours truly when I kill someone you like.

Yeah, I think that's it. See ya!