As the moon reaches its peek in the night sky a familiar boy is laughing maniacally in his room. The room is completely dark except for few lighted up candles. A young boy opens a book to a page where it's labeled as the cursed mirror.
"Hahaha now this is the perfect time to get revenge on the pines family. With this special mirror I would push Mabel and Dipper into a different dimension and they will never be able to get home. Ahahahaha! Soon the mystery shack will be in my possession!"
The young boy closes the book and one by one blows out the candles until there is nothing left but darkness.
"Hey dipper catch!" says I young girl wearing a brightly hand made sweater. She throws a Frisbee at a young boy who fails to catch and hits him right in the nose and fall to the ground.
"Ow! My nose!"
"Oh my gosh Dipper!"
"What, What!? Is it bleeding? Am I going to die!? Oh my gosh I think I'm getting a little woozy. I'm probably loosing a lot of blood right?"
Hahaha oh Dipper. You are so much fun to mess around with. Your fine,"
"Not funny Mabel. That Frisbee really hurt. You really should watch where your throwing," said the young boy, as he got him self off the floor and brushed the dirt from his clothes. As the young girl, Mabel and the young boy, Dipper where playing a 1965 el Diablo convertible pulls up and a old man walks out. He walks towards his trunk pulling out a mirror.
" Come… on… get out…. Of the…. Car. Hey kids! A little help here?"
"Sure thing Grunkle Stan!" said Mabel as she skipped towards her great uncle. As for Dipper he just rolled his eyes and trudged towards the car. He was thinking that it was another type of junk his great uncle got from the junk yard or something.
"So what did you bring this time Stan? Is it another weird monster or a weird object looking thingy?"
"This here Mabel is a mirror. It says to be cursed and on a full moon it opens a magic portal to another dimensions for about 3 days,"
This brought Dipper's attention.
"So I stole it from that tourist stealing creep, Gideon," As the old man continued to pull the mirror out of the trunk, Mabel was reaching out her hand to touch it when her brother stopped her.
"Dipper what gives?"
"Mabel it could be dangerous, you know how things are in Gravity Falls," said Mabel's brother.
"Dipper its just a mirror it not going to suck me into a different dimension. It's probably some rumor someone made up," said Mabel as she argued with her younger twin brother.
As they argued a young boy we've seen earlier is spotted behind a tree spying on them.
"Haha yes, my death trap has worked. Soon I would get my revenge on Dipper pines for coming between my sweet Mabel. As tonight is the full moon and after Dipper and Mabel are gone I will take over the shack! Ahahahaha!"