Chapter 1: The Grey Platform
"It's okay Mabel," Dipper says, holding his sister's face close to his chest, "it wasn't your fault. It was never your fault."
"Kid," Stan says, looking up at the black portal on the roof of the Mystery Shack, "we're running out of time. Are we gonna do this or what?"
Dipper takes in a deep breath and lays Mabel's lifeless head on the ground. He stands up, fixes his collar and puts Journal 3 back in the bag with Journals 1 and 2. "Yeah, we are, Grunkle Stan. This time, Bill will be defeated."
"I just have one things to say you you, kiddo."
"What is it?"
"I'm proud of you." Stan runs into the Mystery Shack. Dipper, stunned by Grunkle Stan's words, smiles. That was the motivation he needed. It was the motivation he needed to take Bill head-on. After Bill succeeded in his plans for the apocalypse, all of Gravity Falls stood still in Bill's dimension. Everything is grey and still. The birds stopped singing their songs, the wind stopped blowing, and the sun stopped shining. Everything feels so…unnatural. It was his fault Mabel died. Dipper was too harsh to her sister and, like he did once upon a time, she made deal with Bill. But as a price, the demon took her soul. She's now trapped inside Bill's world and he must get it back, and save all of Gravity Falls—and the world.
Dipper runs into the Mystery Shack, climbs up the stairs into the attic and makes it onto the roof. He passed Soos and Wendy. They were holding back the hordes of zombies Bill summoned from the basement. That's where Bill took control of Stan's portal. In a few hours, Bill is going to unleash a horde of terrifying monsters onto the world, and with that, he will destroy this world and everything inside this universe like he did countless others. Grunkle Stan and his brother stopped him before, so maybe now they can stop him again. But this time, Stan knows Bill is waiting for him to come. He'll be able to finish off
The black portal sits where the S in "Mystery Shack" is supposed to be. The portal emits a wave of uncanny discomfort for those within a twenty meter radius of it. Dipper, hesitantly, steps inside.
He falls, yet he doesn't fall. It only feels like he's falling. He sees Grunkle Stan getting larger by the second. He must be waiting for him. Dipper swims over to his great-uncle in the darkness and lands on a gray platform next to Stan's feet. Stan helps Dipper up.
"Ah, I remember this place," Stan says. "Kid, if you don't want to die stay close to me. I'll take you as far as I can, but I can't fight Bill. You have all three Journals and you know the spell that can imprison Bill."
"But Grunkle Stan, we can beat him together! I'll give you one of the book and—"
"Kid, I can't do that," Stan says, almost depressed, "you're the only one that can save us now. Come on." Stan turns and starts walking. Dipper follows.
Dipper wonders if Stan knows what he's doing. Every turn he makes looks like directionless guesses and half-witted decisions. They've hit a couple dead-ends twice. This entire time it feels like they've been wondering through a labyrinth without an end. Bill is here somewhere, watching them with his all seeing eye. Stan makes another turn, and another. The grey platform beneath them only shows where they've walked and not where they're going to walk. Dipper guesses he actually must know where he's going.
Coming to trust Stan again was difficult. All he ever did was keep secrets from them—the portal in the basement, how he knew about the Journals the entire time, how he told Soos not to say anything to them about what he knew of Stan's past and the Journals—it was like he even lied to them about being his Grunkle Stan. Was Stan even his real name? But that's all over now.
"Whoa!" Dipper sees Stan fall in the darkness.
"Grunkle Stan!" Dipper runs over to Stan. He's hanging from the edge of the grey platform with only a few fingers keeping him up.
"Kid! Help me up! I'm slipping!" Dipper says nothing more and grabs Stan's wrist with both his hand. He's too heavy. Sweat drips down Dipper's face while he struggles saving his great-uncle.
"Stan—agh!—you're too heavy! I can't hold on to you any longer!"
"No, no, kid, come on, you gotta try! I can't die here!"
"I'm try—" Dipper's hands couldn't hold on anymore. Stan flails his arms, screaming, trying to catch hold of the platform. He falls. He falls into the darkness. "GRUNKLE STAN!" Dipper pauses. "Grunkle Stan?"
Stan picks himself up from the ground. There's a grey platform under him. "Ha! Hahaha! You thought you'd kill me off, Bill?! Good luck!" Stan laughs maniacally out of relief of surviving that fall. He thought he was gone for good. "Dipper! I don't know if I can get back up to you! You have to go on without me!"
"But Stan!"
"Just go! I believe in you! I'll find my own way back!"
Dipper stares at Stan as he walks away. I can do this, he tells himself. I can do this. Dipper stands up, takes in an extra long breath and walks in the other direction in search for Bill.