In the final confrontation between Bill and the remaining townspeople, the Pines family must make a great sacrifice or be defeated by this otherworldly invader.
As Bill and his friends attempt to expand their realm of weirdness, Dipper and the gang run into some unexpected problems while trying to rescue the imprisoned Mabel.
Bill Cipher leads his gang of weirdos through the interdimensional rift to wreck havoc on Gravity Falls.
While Mabel is busy planning her and Dipper's upcoming 13th birthday party, Dipper and Ford venture under the town where they discover its most shocking secret yet.
Grunkle Stan takes the kids on a road trip to sabotage all the other tourist traps in Oregon.
Ford gives Dipper some information about Bill. Meanwhile, Mable and the girls set out to find a unicorn so that they can use its hair to protect the Mystery Shack from Bill.
Grunkle Stan runs for mayor, so Dipper and Mabel try to help their gaffe-prone uncle become the perfect candidate.
Dipper receives his favorite board game in the mail and gets his great uncle to play with him. Unfortunately, the game's wizard materializes in Gravity Falls and they must find a way to defeat him.
Grunkle Stan is forced to reveal his history with his twin brother to Dipper and Mabel.
After government agents take him into custody, the twins uncover some things that cause them to question how much they know about their Grunkle Stan.
Dipper tries to rid the Northwest Mansion of a ghost before it wreaks havoc on Pacifica's upcoming party.
Mabel takes matchmaking too far when she steals a love potion from a real love god.
Mabel and Dipper's attempts to celebrate Soos' birthday get interrupted by the time traveling Blendin's quest for revenge.
The kids discover there is a secret society in Gravity Falls.
This episode consists of Stan telling three different stories. The first one, Hands Off, is about Stan getting cursed by a witch. Abaconings, is about Dipper's attempt to get smarter and the last one, Clay Day, deals with Mabel's fear of stop motion animation.
Soos needs a date for his cousin's engagement party, so he uses a dating simulator game to help him to be able to talk to girls.
Mabel puts on a sock puppet rock opera to impress a local puppeteer, but the show doesn't go quite as planned.
Mabel challenges Pacifica to a miniature golf contest.
Dipper's secret journal pages lead him and the gang to the author's hidden bunker.
The CIA showing up during the Mystery Shack's re-opening leaves Stan feeling threatened; that is until he's faced with an even greater threat: zombies!