Mabel ran through the Mystery Museum gift shop, nearly knocking over a little old lady looking at stuffed griffins. After a hurried apology, she was off again. She dashed over to the checkout counter after a quick scan for Ford. Her great uncle was nowhere to be seen, so she had no problems with slapping the big burgundy book in her arms onto the counter with a thud.

The people at the checkout counter — Dipper, Robbie, and a few customers — jumped at the sound. "Ow, Mabel, that's loud!" said Dipper.

"You're loud all the time," she shot back as she flipped the Journal open. "You have to look at this," and she stabbed a finger at the page. "There's a Bottomless Pit in the forest, and Fo—" She paused and glanced at Robbie. "The Author would throw stuff in, and sometimes it would come out, and sometimes it would be gone forever, and he couldn't find any correlation—"

"Sometimes," Robbie interrupted, accepting money from a tourist and not looking at Mabel, "I find it fascinating that the two of you can both speak at a mile a minute."

Mabel flushed but pressed on. "There's this old paper with the Author's trials on it, and I think I found the secret to the Pit!"

Dipper's expression told that he had no idea what was going on, but he wanted to look excited because Mabel was excited. "So, what is it?"

"Lunar cycles," Mabel said triumphantly. "He's mentioned them before, in relation to Portal Potties—"

"To what now?" Robbie glanced over at them. "What is that book, anyway?"

"U-um," Mabel stuttered. "It's, um—"

"It's this crazy book about supernatural stuff!" Dipper blurted. Mabel shot him a glare when Robbie wasn't looking, but the twin winked in return.

"Sounds like there's some interesting stuff in there," Robbie said, sounding amused.

"There is!" Dipper said. "Mabel loves it, because she's way into magic stuff. Sometimes, she even thinks it's real."

Mabel caught on then. "It is!" she protested.

Dipper shrugged and gave Robbie a knowing look. Mabel frowned; she wasn't sure she enjoyed being the scapegoat of this little fib.

Robbie looked between Mabel and Dipper, then laughed. "You kids are pretty—"

"Excuse me, sir," said a voice cracked with age. "Does this griffin plushie come in any other colors?"

While Robbie turned to deal with the old lady (the same one that Mabel had run into a few minutes before), Mabel leaned towards Dipper and jabbed a finger at the Journal. "I can't be sure until I test it myself," she said in a conspiratorial whisper, "but I'm almost positive that things are more likely to reappear around a full moon."

"Wouldn't Ford have figured that out himself?" Dipper asked, forgetting his excited act. "I mean, he's been doing all sorts of boring stuff like that for years, hasn't he?"

Mabel gave him a withering look. She liked it better when he pretended to be interested. "For whatever reason, Ford lost or got rid of the Journal. He probably wouldn't want to restart all his calculations. Anyway, the correlation is faint; but there's going to be a lunar eclipse tonight, so just imagine—"

"Oh, hey, the lunar eclipse!"

Mabel looked up. Robbie had finished talking to the old lady and was apparently listening to the twins' conversation. "Y-you know about it?" Mabel asked. Could he be into astronomy too?

"Sure," Robbie said. "The squad and I always go out camping during eclipses. It's a fun tradition of ours."

Mabel's face fell. "Oh," she said quietly. Robbie didn't seem to hear her.

"There's one just this weekend," Robbie continued, "so we're all gonna camp out by the Big Rock."

"Fun!" Dipper said. "Who's in your squad? I've always wanted a squad. Do you draw funny pictures of yourselves?"

Robbie chuckled. "No. You've already met Wendy—"

"Oh," Mabel muttered, having lost all of her earlier eloquence.

"—and then there's" —he started listing them off on his fingers— "Natalie (or just Nat), Lia, Thompson, and Tambry."

"You and Thompson are the only boys?" Dipper asked in wonder.

How very brave of you, Mabel thought sarcastically.

"Well, yeah," Robbie said. "We've all been friends since forever, though, so it isn't weird." He laughed. "Sometimes it feels like I'm the only guy, since Thompson is on his phone all the time."

Dipper nodded slowly, and Mabel felt a sting of resentment that he was engaged in this topic when he'd been bored during hers. "Hey," he said suddenly, "how do you camp in the winter?"

"Oh, we drive out to my dad's old yurt," Robbie said. "It's been our family camping site for generations, and it's pretty warm."

Dipper wrinkled his nose. "What's a yurt?"

Mabel sighed quietly and leaned against the counter with her head resting in her hand.

"It's like a tent for the winter," Robbie explained. "It sits on top of the snow and stays warm inside. In fact, I'd better go get the camping beds after—"

"Robbie Corduroy!"

Every head in the gift shop turned as Stanford Pines burst from the Employees Only door. Mabel acted without thinking: She slammed the Journal shut and pushed it off the counter towards Dipper, who, thankfully, caught it and moved it out of sight.

Ford didn't seem to notice the exchange. He thundered up to the counter, and Mabel shied back as she saw the look on his face. He was angry. She felt a flash of fear that he had found out about the Journal — but he was focused on Robbie, not her.

"Is this some sort of joke? A prank your friends pulled?" Ford demanded. He braced his six-fingered hands on the counter and towered over Robbie.

Robbie's eyes were wide. "I don't know what you're talking about, Mr. Pines," he said. He seemed scared, but his voice was steady.

"You don't know what — my axo—" Ford stopped, his eyes narrowing. "You don't know anything about a robbery?"

"A robbery?" Robbie repeated. "Someone stole from you?"

"Yes! Something very important! You swear it wasn't a prank from you or your friends?"

Robbie glanced around the gift shop at the tourists, who were all watching the exchange. "Maybe we should talk about this somewhere else."

"Robbie," said Ford in a low but forceful voice.

"If my friends pulled this off, they didn't tell me about it," Robbie said. "What was stolen?"

"A — never you mind. A project of mine. Does this sound like something your friends would do?"

Robbie shook his head. "If they wanted to pull a prank on you, Mr. Pines, then they'd vandalize your merchandise. And get me in on it. I'd be their access guy."

Ford's eyes narrowed. "We'll talk more about that later." He pushed off the counter and stood up straight, running a hand through his hair.

"Ford," said Dipper, "shouldn't you call the cops if you were robbed?"

Ford looked at Dipper as if he had just noticed the boy. "Um, yes, I should," he said. Then he turned and left the gift shop, muttering to himself the whole way out.

There was silence from the customers. Robbie turned to the twins and shook his head. "If someone stole one of his projects, then he's not gonna call the cops about it."

"What do you think it was?" Mabel asked.

"Who knows," Robbie said. "Man, the old guy can be fierce when he needs to be."

Mabel and Dipper nodded.

"A robbery," Dipper said, leaning on his elbows. "That's kinda cool, actually. Who do you think did it?"

"A tourist, probably," Robbie said. "It's a good excuse to get out of town before you're caught."

"Yeah, but if they just stole one of Ford's projects, wouldn't it be someone who knows him?"

It felt like the conversation about the Bottomless Pit was years ago. Mabel sighed. Why did she always get sabotaged when she tried to talk about these things?

The Employees Only door banged open again, making Mabel jump. Ford was back, and he looked even more angry. "You three, living room, now," he said, pointing at Mabel, Dipper, and Robbie.

Robbie and Dipper got up and headed towards the door (Robbie seemed unconcerned about the customers waiting to buy trinkets), but Mabel stayed back for a moment to grab the Journal and stuff it in her hoodie.

When they caught up to him, they found Ford pacing in front of the couch. Robbie began, "So, there are customers—"

"They stole money, too."

Silence.

"How much?" Dipper asked.

Ford sighed. "Not enough to give us financial trouble, but enough to make a mark. This was a very obvious robbery, kids, which makes me think — or, at least, hope — that it's just a prank."

"I'm still innocent," Robbie put in. "When did this robbery happen, anyway? Last night, or just now?"

"The money was stolen while I was talking to you just a few minutes ago."

The silence returned, this time heavy. That meant the thief was possibly still in the building.

"And the project?" Mabel ventured.

"The last time I saw it was just this morning. There were only a few hours for the thief to come. After I saw the project was gone, I checked the money, then went to the gift shop. Afterwards, I checked the money again, and some of it was gone."

"Grunkle Ford, you gotta call the cops if your money was stolen," Dipper said.

"Yes, fine," said Ford, but he sounded distracted. "The thief is still in the Museum, especially if they're disguised as a tourist. The penetrability of my own home is disturbing, to say the least."

Mabel could see Dipper looking slightly confused about the word "penetrability", so she leaned over and whispered, "How easy it was for the thief to get in."

"I knew that," Dipper whispered back.

"They stole two separate times in the same day," Ford continued, "which means they could be haunting us for days or weeks."

"Not if you call the cops," Robbie pointed out.

Mabel gasped. "Haunting? Grunkle Ford, do you think it's a ghost?"

Robbie raised an eyebrow.

"It's not a ghost," said Ford.

"But—"

"Ghosts don't steal; they haunt. They scare people; they break things sometimes; but they don't steal."

"Ghosts can do all sorts of things," Mabel muttered, crossing her arms and looking away.

"Regardless of whether it's a ghost or a person, I want to take some precautions."

"Like calling the cops?"

"I am not calling the cops!" Ford thundered. "Those idiots can't tell one end of a Taser from the other. I am not trusting them to protect my business. Now, with that aside" —it wasn't really aside, but everyone was in too shocked of a silence to interrupt— "I'd feel better if you kids weren't in the house for a while."

Mabel frowned. What did he expect them to do? Go live with Dipper's friends for a few days?

Unfortunately, Dipper had a worse idea. He gasped like he had a brilliant plan and said, "We could go camping with Robbie and his friends!"

The world froze around Mabel — or maybe she was just frozen. No, Dipper. No, that was a terrible idea. We can't. We—

"Camping?" Ford asked.

"Yeah," Robbie said. "My friends and I are going camping this weekend. We're leaving this afternoon. We could totally take these two along."

Please, no. We can't go.

"That's very generous of you," Ford said. "I would love for them to go. That would give me some time to put all this thief nonsense to rest. How about you go finish your shift and then give these two a packing list? I have some extra gear they can borrow."

Mabel wanted to protest, but the sound wouldn't come.

"Yay! Camping!" Dipper turned to Mabel with an excited look on his face, but it slid off as he met her eyes and saw the fear in them.

Mabel finally found the strength to speak. "Can Dipper and I talk for a moment?" she asked. She grabbed Dipper's arm and pulled him off into the hallway way before anyone could say no.

"What's wrong?" Dipper asked when they were out of Ford and Robbie's view.

"What's wrong?" Mabel repeated. "You just signed us up to go spend three days out in the woods with teenagers, that's what's wrong!"

Dipper frowned. "We're teenagers."

"Not like them! To them, we're still kids! You remember Wendy — she was a jerk! When she and the rest of Robbie's friends find out we're coming along, they'll hate us! We won't be able to get away — they'll eat us alive! For once, Dipper, can you think before you get us into these messes!"

"Woah, woah, woah!" Dipper put up his hands. "Mabel, you are freaking out big time. Breathe for a second."

He let the time pass for Mabel to take a deep breath. It didn't help.

"Listen," he said. "They're only three years older than us—"

"Three years is a big difference! They're juniors! We're only eighth graders! We're still in middle school, and they're—"

"Mabel. Calm down. Robbie is nice, and I bet his friends are, too. If we don't act like kids, they won't treat us like kids. And if Wendy is a jerk, so what? Robbie will look after us."

"I — I—"

"It'll be okay," Dipper said. Then he smiled. "And hey, isn't the Bottomless Pit near their camping spot?"

Mabel frowned. "How did you know that?"

"Lucky guess. Maybe you could get over there and study it instead of hanging out with Robbie's friends all day."

Mabel looked into her twin's eyes and searched them with her gaze. Wow. He really thought he hadn't just sealed their doom.

"Although," Dipper continued, "I thought you'd be excited to spend more time with Robbie, what with your cru—"

"Dipper!" That did it. Mabel glared at her twin, then sighed and shook her head. "You can go. I'm gonna get myself out of this."

"Mabes!" Dipper protested.

But she was already gone.