Secret of the Vending Machine

That evening, when they were shutting down the gift shop for the day, Dipper left the security cameras turned on.

"I'm not sure this is going to work," Dipper said. "There's a light on when these things are running. He'll see it and know they're going."

"Every problem can be solved with stickers," said Mabel. She jumped up and stuck a heart sticker on the light of the first camera, that had a view of the front of the gift shop. "Boop!" Then she did the same to the camera with a view of the back of the gift shop. "Boop!"

They had a restless night. Dipper stayed awake for a long while, trying to listen, but he eventually fell asleep.

Early in the morning, before Stan was awake, Dipper and Mabel rushed into the shop and played the tape. (They also also removed the stickers.) They got a shock. Grunkle Stan came into the gift shop, pressed buttons on the vending machine in a certain pattern, and opened a secret passage. Then he disappeared inside.

"Wow! Like, what was that?" said Mabel.

"We're going to find out," said Dipper.

At breakfast, Dipper said. "Grunkle Stan, why didn't you tell us about the secret passage behind the Gift Shop vending machine?"

Stan did a spit-take with his coffee. "Huh? What are you talkin' about? A secret passage? I don't know nothin' about it."

"We have photographic evidence of you going in," said Dipper.

"Yeah! They don't call us the Mystery Twins for nothing," said Mabel. "You have a right to remain impressed with our great detective work."

"I have a right to remain angry that you were spying on me!" said Stan. "That's my private basement. Off limits."

"To think we were about to trust you and show you the Journal!" said Mabel.

"Huh?" said Stan. "What's this about a journal?"

"We wanted to know if we could trust you with something big," said Dipper. "Looks like we can't. We've got it well hidden, and it will stay that way until you show us what's down there and tell us the truth."

Stan looked frustrated. "All right, I'll show you, but you have to keep your hands off of things down there. It's dangerous."

"Dangerous is our middle name," said Dipper.

"It's not, but we're still super interested," said Mabel.

Stan got up from the table. "All right, come on."

He led the way to the vending machine and entered the code. They walked down a flight of stairs, to an elevator door. Stan entered a four-symbol code and the elevator opened. They went down to the third level.

In the room was a computer control panel and a huge device on the side of the room that looked like a downward-pointing triangle. The device was powered off.

"Grunkle Stan, what is this? And what are you doing with it?" asked Dipper.

"It's a Portal to other dimensions. I'm trying to get it started again so I can find my lost twin brother, who disappeared through it thirty years. ago," said Stanford.

Dipper and Mabel looked suspicious.

"Grunkle Stan, I think our parents would have told us about a lost great uncle if we had one," said Dipper.

"And Grandpa Ralph Pines isn't missing," said Mabel. "He lives in Florida with Grandma Josephine. Our parents didn't want us all the way across the country, or we would have gone there."

"It seems weird that our folks would send us to a place where a major relative disappeared without saying anything about it," said Dipper.

"There's a Pines brother they don't like to talk about. Stanley Pines, the black sheep of the family. Your parents didn't think it was odd that a shady character like that would take off one night from his brother's house for parts unknown, and that they haven't heard from him since. But that's not what really happened."

"Stanley Pines is even shadier than you? That's really something," said Dipper.

"No, that's not it," said Stan. "I'm Stanley Pines. It was Stanford Pines who disappeared thirty years ago. When your parents sent you here, they thought I was him. I've been using his name."