Gideon Gleeful has taken control of the Mystery Shack, forcing the Pines family to move in with Soos at his grandmother's house. At a press conference, Gideon announces his intentions to turn the Shack into his own personal theme park, Gideonland, which the Pines family see on television. After failing to convince the town of Gideon's true nature, Mabel worries about where they are going to stay if they don't get the Shack back. Meanwhile, at the Shack, Gideon reveals to his father the true nature of his book; the story reads that it was written a long time ago by an unknown author who learned the secrets of Gravity Falls and hid the journals where no one could find them, knowing that when the journals are brought together, it will lead to a gateway of "unimaginable power". However, he is unaware that there are three journals and not two. Gideon says that the codes and maps from the two journals have led him to believe that the remaining one is hidden somewhere on the Shack's property.

Meanwhile, Dipper and Mabel are told that they are heading on the next bus out of Gravity Falls. With advice from the third journal, which they own, they devise a plan to assemble the gnomes that had tried to kidnap Mabel at the beginning of the summer to try to take the Shack back, but the gnomes are stopped by Gideon's pig whistle. The gnomes restrain Dipper and Mabel, causing the former to drop the journal, which Gideon takes. Dipper and Mabel then leave town on the bus. Back at the Shack, Gideon is overjoyed to have the journal he stole from Dipper, until discovering that it is the third journal. Believing that Dipper is trying to get the first one out of town, Gideon takes a giant robot look-alike and goes after their bus.

Upon watching the Gideon-bot, Dipper and Mabel tell the bus driver, Soos, to run. Gideon chases and corners the bus at the edge of a cliff. Dipper and Mabel escape the bus, but Gideon corners them. As Dipper denies having the first journal, Gideon grabs Mabel and throws Dipper aside, planning to rule the town with Mabel as his queen. Dipper jumps off the cliff into the Gideon-bot, where he and Gideon start to fight, with Dipper defeating Gideon. The bot loses balance and falls off the bridge, but Mabel and Dipper are saved by the former's grappling hook. A large crowd surrounds the robot, to which Gideon tries to blame Dipper and Mabel for trying to kill him. As the police prepare to arrest Dipper and Mabel, Stan shows up and reveals Gideon's deception; Gideon had been using cameras hidden inside the pins he had handed out to the townsfolk in order to spy on them. The police arrest Gideon, and Stan takes the deed and the second journal from him. The Pines settles back in the Shack. Dipper and Mabel show Stan the third journal, stating their trust in their great-uncle. Stan laughs, crediting everything the twins told him to be a result of reading the journal, and takes it to Dipper's disappointment, but Mabel cheers him up. t+The twins have a water fight with Soos.

Later that night, Stan takes the third journal and later opens a hidden passage door behind the Shack's vending machine. He walks into a hidden laboratory and goes down an elevator. Revealing that he was the one with ownership of the first journal, he places the three books together, with each opened at a specific page, revealing the blueprint for a machine. He uses codes from the pages to activate the machine.

"Gideon Rises" premiered on the Disney Channel on August 2, 2013, as the final episode of the first season of Gravity Falls and received a viewership of 3.2 million in the United States.^[4]

The A.V. Club gave the episode a grade of "A", concluding "No single half-hour could wrap up all the questions Gravity Falls has raised over this season, but this episode shows an impressive knack for knowing which questions need answering and which can be safely ignored. And the biggest question it answers isn’t even really on the radar until the final minutes of the episode, as Stan finally reveals just how much he's been fooling everyone all this time. Alex Hirsch nails Stan's reaction to being presented with Dipper's journal, as he can’t quite mask his initial, genuine excitement before returning to his oblivious disguise. It's still not at all clear where this is all headed towards, but the show appears on the verge of changing irrevocably."^[3]

The episode was nominated for a Golden Reel Award under the category Best Sound Editing - Sound Effects, Foley, Dialogue and ADR Animation in Television.^[5]

• "Gideon Rises" at IMDb