In this episode of Gravity Falls, the ominous hints of Billy’s plans come to fruition and viewers are left to wonder what fate awaits the town.

It starts innocently enough, however: Mabel wakes up Dipper with a funny voice she used to do from their childhood and notes that in one week (the same time summer vacation is ending) the two of them will have their 13th birthday and become teenagers. To celebrate this milestone, Mabel begins planning a massive celebration. As Stan is not excited to pick up more rotting flesh from the last party at his house, Soos suggests having a party at the high school gym.

Suddenly, hopes for a fun party are interrupted by an explosion caused by Ford. Dipper comes running and find that he has been tasked with saving the universe once again. Ford explains that the dimensional rift he’s sealed is beginning to break and needs to be patched back together to prevent a catastrophe. Dipper is excited for his first mission with Ford but feels a little bad about leaving Mabel to tackle the party on her own. But she shrugs it off and continues working on the party.

While Dipper and Ford are investigating an ancient giant UFO buried under the town for some extraterrestrial adhesive, Mabel goes to the high school and sees Wendy and the other high school students tremble in fear of another year as teenagers. Mabel begins to think that her unrealistic hopes for a glamorous future (ripped off from cheesy teen movies) is nothing but depressing. But, ever the optimist, she goes to invite Grenda and Candy to the party. Unfortunately, they have things to do on the last week of summer and will be unable to say goodbye when Mabel and Dipper leave Gravity Falls. Mabel tries to call Dipper for advice on the walkie-talkie, but the connection is bad.

On the other end, Dipper is investigating the bowels of the UFO with Ford using a magnet gun. Ford has been down into the ship many times before, assumes the whole thing is obsolete, and is unfazed by it. He quickly repels down with the magnet gun but Dipper has a hard time being as handy with it as his great uncle. Still, Ford reveals to him that he has an exceptional mind and suggests that Dipper stay with him to become his apprentice and investigate the mysteries of Gravity Falls. Dipper is uncertain about a future without his sister and lacks confidence in his ability. Yet, almost as if to contradict his insecurity he stumbles upon the adhesive that the two are looking for. Unfortunately, not all of the UFO is inactive as the security system has been switched on.

A security droid comes and Ford warns Dipper that it detects adrenaline. While Ford is able to keep calm, Dipper panics and is spotted and shot at. Ford pushes him out of the way, but the security system then captures him and takes him to prison. Ford tells Dipper to forget about him and fix the rift, but Dipper uses the magnet gun to ride a careening pod through town. Ford is smacked around as the ride continues, and Dipper finally is able to use a magnetic pulse to crash the aircraft imprisoning Ford. After the crash, though, the droid returns to inspect it but Dipper bravely stands up against it. Not detecting fear, the droid assumes the threat is gone and disassembles itself. Ford wakes up and praises Dipper’s actions.

However, Mabel is lower than ever, assuming her future will be bleak as a teenager. Stan comes in to cheer her up, saying that Dipper will be with her even if she leaves. She feels assured until she overhears the walkie-talkie reveal Dipper’s decision to stay with Ford and leave Mabel by herself. Later, when Dipper returns, the two fight about his decision and Mabel runs off, furious at her brother’s insensitivity.

Mabel sits by herself in the forest and does not realize she accidentally brought Dipper’s bag with her. Hearing Mabel express that she wishes summer could never end, Blendin Blandin, the time traveler from previous episodes, arrives and offers Mabel a way to grant her wish. All she has to do is give him a “gizmo” that Dipper has. Finding the sealed rift, she hands it over and Blendin reveals himself to be Billy possessing Blendin’s body. Expressing extreme delight, he breaks the rift and the sky begins to open up.

The end has no joke and no preview. All that is left are the noises of Gravity Falls being under attack over the cute poster of the twins’ birthday party. Until next time, curiosities are definitely piqued to see what happens next.