Warning: This prologue contains no canon characters so if you don't want to see an OC only chapter, then I advise you wait for chapter 1.

Disclaimer: I don't own Gravity Falls, only my OCs.

Beep, beep, beep, beep!

The sound of a siren ran through the building. Everyone ignored it and carried on with their work, except for one. The person stopped playing their computer game and typed furiously to find the reason for the siren. Their eyes widened, and they dialled at light speed on a phone.

"Emergency! Another one of them has been spotted! And I'm not kidding this time!" they said to the receiver.

"Yeah, right. How do we know you're not pranking us again, Kate?" the receiver replied.

"No! I swear, this is not a joke! This. Is. SERIOUS!" she claimed.

"Well, how do we know that this is not a very severe one of them?"

Six words changed it all: "I think the government is involved."

The receiver finally recognised the seriousness of the alarm. They did go off for a reason. Action needed to be taken - and fast.

"I'll get one of our best," was the response before the phone was hung up. Kate looked at the computer screen and sighed. I hope this works, she thought.

A girl paced around her dark office, deep in thought. Next to her the phone started to ring. It was a few seconds before she snapped back to reality and answered.

"Talk to me," she said.

"We have a mission for you. More of them have been spotted," the caller explained.

"What, you mean more mystery hunters? Thought we'd fixed the last of them," the girl replied, searching through a desk drawer.

"Well, I'm afraid there are more. And these ones could be seriously dangerous."

The girl shut the drawer she was looking through. "Age of target?" she asked.

"Twelve years of age," the caller replied.

The girl paused. "You want me to take on a couple of kids?"

"Well, they're more dangerous than they look. You won't do it, though?" the caller replied.

The girl laughed. "Oh, I'll do it. I'll make sure your mystery kids never go on another mystery hunt again," she said, pulling out a Swiss army knife.

"Hey, no killing this time. We don't want to draw unwanted attention," the caller ordered.

The girl cursed under her breath and put the knife down. "Fine. Name of targets?" she responded.

"Dipper and Mabel Pines. Local twins in Gravity Falls," the caller answered.

"Got it. Don't worry, I'll get this job done right," the girl assured, grinning.

"We're counting on you, Black Rose."

The line dropped. The girl - Black Rose - sat at her desk and pulled out a file.

"Gravity Falls, huh? Guess it would be nice to see the old town again," she said aloud. She opened the file and looked through its contents. She dialled a familiar number on her phone.

"Kate, I'm gonna need your help for this. It won't be easy alone," she said to the receiver.

"I get to come to your mission? Awesome! So, you're not killing this time?" Kate replied.

"They won't allow it. I'm switching to Plan B. Meet me in my office in five minutes," Black Rose explained, then she hung up. She searched through the file until she found the right plan. Perfect, she thought, smiling. The plan that could save the organisation was ready to be performed.

And in her hands was a small file labelled 'The Notebook'.

A/N: Well, here it is. The beginning of a rewrite of 'The Spirit In The Notebook'. I wanted to start with this prologue, because it seems like it could be an awesome idea. The proper story starts in the next chapter, with the canon characters in it.

Feel free to leave a review, if possible. Constructive criticism is greatly appreciated, as it always is. Feel free to say whether you think this will be a fairly good story or not, it won't be the same as the old story, though.