The truck rolled to a stop, and only when she felt it bump back did Mabel realize what was going on. She raised her head in drowsy confusion, having nearly managed to fall asleep. The drive wasn't that long, but apparently her anxiety about all this made her tired.

"Here we are!" Robbie said. "Our home away from home: the Big Rock."

"Cool!" Dipper unbuckled his seatbelt and leaned forward, waiting for Robbie to let him out. Wendy simply grumbled a bit in the front seat.

Mabel unburied herself from the gear she was under, frowning at the back of Wendy's seat as she did so. Girlfriend. . . She was Robbie's girlfriend? How did he put up with her? She hadn't said one nice thing since getting in the truck. Why would he even fall for her?

And why was Mabel suddenly so jealous?

She frowned at herself. You always knew you'd never have a chance with Robbie, she told herself. Thirteen-year-old girls don't date sixteen-year-old guys. It doesn't happen! The fact that he already has a girlfriend has nothing to do with it.

But it still made things worse, somehow.

"Hey, grumpy," Robbie said to Wendy. Mabel could see a small smile on his face as he looked at her. "How about a smile on that face?"

Mabel couldn't see Wendy's expression, but after a moment the teen leaned over and gave Robbie a quick kiss. "All right," she lamented. "For you."

Suddenly, Mabel wanted to bury herself under her camping gear all over again.

Another agonizing moment passed before Robbie spoke up. "All right, let's get all this stuff out of here." He reached around his seat and poked Dipper's knee. "Like you."

Dipper laughed. "Hey!"

Robbie got out of the car and pulled the seat forward for Dipper, who bounded out immediately. For Mabel and Wendy, the process took much longer. Neither of them acknowledged the other as Wendy pulled the seat forward and Mabel slid down to the ground. The Journal, which was under her arm, nearly slipped out, and she fumbled to catch it.

Snow crunched beneath her feet as she joined Dipper and Robbie on the other side of the truck. She still wasn't sure if camping in the winter was a good idea, but that seemed to be the least of her problems at this point. The boys pulled stuff out of the backseat, throwing it on a tarp that Robbie had laid on the snow. "Dip," said Mabel softly.

Dipper turned, dropping a sleeping bag onto the tarp. "Yeah?"

Mabel pulled him aside as she saw Wendy coming around the truck. "C-can we go?" she said.

Dipper frowned. "Shouldn't we help set up?"

Mabel shivered in the cold. "I think we'll just get in the way. C'mon. We can go find the Bottomless Pit, maybe, or. . . or we can just get away."

Dipper was silent for a moment, searching his twin's face. "I'm sorry Wendy was rude to you."

"I-it's not that. Please?"

Dipper hesitated, then nodded. "All right. Let me go ask Robbie if it's okay."

Mabel stayed where she was as Dipper rejoined Robbie and Wendy. "Hey, is there anything we can do to help?"

Mabel groaned softly. Dipper, she thought, you don't offer our help when we're trying to get out of it!

Robbie gave a small laugh. "You guys can go explore while we get settled in. Don't go too far, though. Mr. Pines would have my head if you guys got mauled by a bear or something."

"Don't bears hibernate in winter?" Dipper asked.

Robbie waved a dismissive hand. "You get my point."

Dipper bounced back over to Mabel. "There! Now we can go," he said with a smile.

Mabel was both grateful for his enthusiasm and resentful of it at the same time. Nevertheless, she followed as he made his way to the surrounding woods. "So, where is this Bottomless Pit, anyway?" he said.

Mabel pulled out the Journal, flipping to the page on the Bottomless Pit. "The directions are all smudged, probably from Ford's own arm while he wrote some of these footnotes." She gestured to the small, cramped lines written sideways in the margins. "But I can make out 'large rock' and 'clearing,' so I think Robbie's Big Rock is close to it." She stopped, looked around, and pointed decisively to their right. "This way." She didn't really know where they were going; but she wanted to look like an adventurer, and they always chose their paths well.

The twins trekked through the snowy forest in silence. Though it was chilly, Mabel was grateful for the fresh air after that car ride. It hadn't been the longest drive she'd ever taken — especially if you counted the bus drive from Piedmont to Gravity Rises — but the negative mood hadn't done anything to help it go any faster.

Dipper suddenly stopped. "Do you hear something?"

Mabel stopped too, listening. "No."

Dipper frowned, squinting into the distance as if it would improve his hearing. "Listen."

Mabel listened. At first, she could only hear the still, silent air; but when she strained her ears, she could hear something. It sounded like distant voices.

The twins shared a glance, then started moving toward the sound. A single voice increased in volume until it was shouting, but they couldn't make out what it was saying or who it belonged to.

Then, with a last shout that echoed faintly through the trees, the voice cut off.

"Can you still hear it?" Mabel asked.

"No," Dipper said. "It just. . . stopped."

They waited for a moment but could hear nothing else.

"I say we investigate," said Dipper. "It could be a wounded magical creature!"

"Or an evil magical creature trying to trap us."

"We'll be fine," Dipper said. "And isn't this all about adventure? C'mon!" He started running toward the direction of the voice (as best he could in the deep snow), and Mabel had no choice but to follow after him.

"Dipper!" she panted. "We can't — just—" But the physical exertion it took to run through knee-deep snow was too much for Mabel, and she stopped trying to talk.

They kept running. Mabel was about to demand they stop for a rest when Dipper yelled out. "Woah!" His arms pinwheeled as he stumbled back.

Mabel grabbed his shoulders and steadied him. "What happened?" she asked when he was balanced.

"Cliff face. Almost jumped right off it."

Mabel looked down. Sure enough, the snow ended abruptly, hidden by low-hanging tree branches. Mabel bent down and inspected the cliff. "Wow. There's a whole little clearing down there, it looks like."

"Maybe the Bottomless Pit is down there," said Dipper, crouching down next to her. She noticed that he favored one ankle and rubbed the other absently, though it thankfully didn't look like he had twisted anything.

"Maybe," Mabel said. "Wait, Dip, do you see. . . ?" She leaned forward.

"See what?"

"Something. . . purple."

The moment she said it, a gust of wind nearly knocked the two of them onto their backs. Mabel instinctively closed her eyes; when she opened them again, it took her a moment to figure out that something was wrong.

The world was grey.

Everything had gone to greyscale: the trees, the snow, the sky. Only Dipper, who knelt beside her with a shocked expression on his face, still had any color to him. "D-Dip," Mabel said slowly, "are you seeing this?"

"I think so," Dipper replied, equally slow.

"I've got it!" exclaimed a voice.

Mabel nearly jumped out of her skin. She knew that voice. She'd recognize that voice anywhere.

It was coming from below them. The twins shared a look, then simultaneously reached for the pine boughs in front of them. Carefully, they lifted them enough to peek through.

Pacifica Pleasure stood in the valley below. "That employee," she said, "the one going on the camping trip with the Pines twins. I hoped they wouldn't be around to suspect anything, but it'll have to do."

Across from her, listening intently, was Bill Cipher.

Mabel recognized him instantly. How often had she stared at his page in the Journal, wondering who he was or how Ford had discovered him? How often had his very image sent a chill down her spine? And now he was actually here. He looked very similar to his picture in the Journal, except that he was bright yellow.

"If we play our cards right, they won't suspect a thing," Cipher said to Pacifica. His voice echoed with multiple layers.

They. Who was they? Mabel's brain backtracked to what Pacifica had said before and realized that "they" meant the Pines twins. That couldn't be good. She wanted to shy back before either Pacifica or the triangle could see her or Dipper, but she couldn't bring herself to move away. Instead, she watched from above as Pacifica nodded in thought.

"Bill," the showgirl said, "could you search the employee — Robbie, I believe —for information about the deed to the Museum? If it's in a safe, what the code is, stuff like that."

Mabel and Dipper shared a concerned, confused look. Robbie? What did they want with Robbie? Why were they talking about the deed to the Museum?

"Sure can!" Bill replied. "Robbie Corduroy, huh? I haven't explored his head much."

A shiver went up Mabel's spine. "Explored his head"? The Journal called Bill a dream demon. What exactly did that mean? What was Bill going to do to Robbie?

"So you'll do it?" Pacifica said. The hopefulness in her voice made Mabel sick to her stomach.

"Absolutely, kid. What will you do for me in return?"

"I don't know. What do you want?"

"We can work out the details later, if you want." The triangle — the demon — held out his hand, and Pacifica took it. Blue fire spread across their hands as they shook.

"Deal," Pacifica said with a smile.

Multiple alarms went off in Mabel's brain. She felt Dipper tense beside her; they both felt the seriousness of what was happening in that valley, even if they didn't entirely understand it.

Bill floated up a little higher and spoke with a smile in his voice. How he spoke, Mabel wasn't sure; he had no mouth, but he flashed a brighter yellow with every syllable. "Well, time to invade Robbie's mind! This should be fun!"

"Wait!" said Pacifica. "How will I know when you've gotten the information?"

"I'll show up in your dreams tonight," Bill replied. "That's how most people meet me, like Lone Wolf here. I do like it when I'm summoned, though. It means I get to make deals."

His yellow glow grew brighter by the second as he rose even higher in the air. "Well, I'll see you tonight, Crescent Moon!" he said. He said the words to Pacifica; yet, at the last second, Mabel could've sworn that he looked right at her.

Then Bill grew too bright to see anything, and Mabel squeezed her eyes shut against the light.

When she opened them, the world around her was back in color, and the demon had disappeared.

"Who was that?" Dipper whispered beside her. Mabel studied his face in the sun's fading light and saw confusion and fear in his expression.

"Come on," she whispered back. She wanted to get away from Pacifica as soon as possible.

The evening forest was silent as the twins stood up shakily and started walking back the way they came. Mabel knew they had to go faster, but she couldn't bring herself to move quickly through the deep snow. "His name is Bill Cipher," she explained as they went. "There's an entry on him in the Journal. It doesn't go into a lot of detail, but. . . it calls him a 'dream demon'."

"What does that mean?"

"I don't know. It means Robbie is in trouble." She tried to pick up her pace, but the panic was setting in now; instead of giving her energy, it sapped her of strength.

Dipper grabbed her hand. "Then we have to hurry," he said, and he tugged her along.

She stumbled behind him. "I — I don't think I can."

Dipper stopped and turned to his sister. In the dusky light, she could still see the clear determination in his face. "Mabel, we have to get to Robbie," he said firmly. "Now."

The twins locked eyes. Mabel's brain processed Dipper's words sluggishly as her mind begged her to stop and think about all this at a different time. But she couldn't shut down. She had to move.

"Now," she repeated, and she forced herself to run through the snow at Dipper's side.

~~~~~

As Dipper ran, the world around him inked to black.

It wasn't until he almost tripped over his own feet that he realized he couldn't see anything anymore. He could hear — Mabel was still running and panting behind him — but they had better find the campsite soon, or they'd be stranded in the cold, dark forest with no way to help Robbie.

He still wasn't sure how they were going to help Robbie, or even why he needed their help.

Mabel's breath huffed in his ear as she ran alongside him. He hoped she was okay; she seemed to be staving off panic. But the concerned brother in him was overridden by the situation. They had to tell Robbie what they had heard!

"D-Dip — Dipper, I can't s-see!" Mabel's footfalls slowed, and she gasped for air. He stopped and turned to her. He thought he could make her out, just slightly.

"Do you—" He was gasping for air, too. "—have a flashlight?"

"No!"

Dipper moaned to himself. "I should've brought my light-up shoes. Mabes, do you. . . do you think we're going the right way?"

It was the wrong thing to say. Mabel immediately started to hyperventilate. "Oh my gosh, we're lost out in the middle of the forest — and we're going to freeze to death — and they'll find our cold, dead bodies buried under the snow weeks later — and—"

"Woah, woah, Mabel! That's not what I meant! It's okay!" He fumbled through the snow, meaning to give her a hug, but he just ran into her. She laughed a bit despite herself as they collided.

A sudden bright beam cut through the darkness, hitting Dipper directly in the eyes.

"Gah!" He fell back, landing in the snow. It immediately soaked through the seat of his pants, which reminded him once again of how wet, cold, and miserable he was. At least he wasn't stupid enough to wear shorts today.

"I found them!" a voice yelled. "I found them! Guys? Over here!"

Was that. . . ?

Dipper blinked rapidly until he was no longer blind. He could now see Mabel as she shivered and squinted into the light. He thought he recognized the voice, but he couldn't tell.

"There you idiots are! When Robbie said to go exploring, he didn't mean wander around after dark! Now I'm stuck searching the stupid woods for you—"

Dipper covered his ears. Yep, that was Wendy.

Mabel pulled him to his feet, and they both made their way to Wendy's light. "Where's the campsite from here?" Dipper asked. "We kinda got lost."

"No duh," Wendy replied, and Dipper thought he saw her roll her eyes behind the flashlight beam. "It's back that way. Robbie's there waiting, and he's worried about you guys. Which means the rest of us had to come looking for you in the dark."

Mabel was quiet; Dipper knew her pride was wounded. "Sorry," he said for both of them, though he didn't really mean it.

Then it hit him again. The triangle guy. Robbie.

As Dipper's mind raced, his mouth went with it. "Wendy, thank you for finding us — can we please go back as fast as possible? 'Cause we really really need to tell Robbie something — plus it's freezing out here, and—"

"Woah, kid, put a sock in it," Wendy said with a scowl. "Just follow me and shut up."

Dipper met Mabel's eyes; they both frowned, but they followed Wendy without saying anything.

It was only a few minutes before they got back to the tent thingy — right, the yurt, that's what it was called. Dipper started running for it as soon as he saw the faint glow coming from within. "You said Robbie was in here?" he called back to Wendy, but he didn't wait for confirmation. He ran up the wooden steps and threw the door open.

"Robbie! Robbie, you're in—!"

He stopped and stared. While he was frozen, Mabel ran into the yurt and came to a stop next to him. The twins turned to each other, then back to Robbie. "He's asleep," Mabel said unnecessarily. Robbie was slumped in a camping chair, sleeping peacefully under the lamplight. "D-do you think. . . ?"

"Wendy said he was worried about us," said Dipper. "Why would he be asleep?"

Mabel turned wide eyes to her twin. "Bill must've done something."

"So. . . we're too late?"

Mabel's eyes narrowed in determination. "No," she said. She pulled the Journal from her sweater and flipped through it frantically until she found the page with Bill, which was half-torn and spattered with blood. "'It is possible to follow the demon into a person's mind,'" Mabel read, "'and prevent his chaos. One must simply recite this incantation.'"

"Follow him?" Dipper asked. "As in, go into Robbie's mind?"

Mabel paled, then nodded firmly. "We have to," she said, probably more for herself than Dipper.

He took a deep breath. "Okay. Let's do it."

Mabel scanned the Journal. "All right. Put your hand on Robbie's arm, or something."

The twins stepped forward on either side of Robbie, each placing a hand on his arm. (Mabel blushed a bit as she touched him.) She kept her eyes locked on the Journal and took a deep breath. "Videntus omnium," she chanted. "Magister mentium."

The lamplight flickered.

"Auxilium ad hominem. Magnum opus."

The wooden door banged open again, making Mabel jump. "What on earth are you two doing?" Wendy demanded.

Dipper's eyes widened. Bad timing, Wendy!

He saw Mabel's expression harden, and she continued chanting. "Auxilium ad hominem! Inceptus Nolanus mirabilis!"

The lamps went out, and the room started glowing blue. With a start, Dipper realized the light was coming from Mabel's eyes. From his eyes.

"Stop doing that! Get away from my boyfriend!" Wendy advanced on them.

Mabel was nearly shouting now. "Magister mentium!"

Wendy reached Dipper, and she tried to push him away.

"Magister mentium!"

"Wendy, wait, stop, you can't—"

"Magister mentium!"

The blue light grew so strong that it obscured Dipper's vision entirely. All he could feel was his hand on Robbie's arm and Wendy's hand on his.

Then even that disappeared.