The Greens prepare for their Halloween party and Tilly secretly "borrows" Gwendolyn Zapp's alien chemical compound to make Bill's pumpkins grow bigger but it also mutates them into body-snatching alien monsters.
It is Halloween time once again and the Greens and Gloria are hoping that this year's events will be better than last's. Meanwhile up on Mars, Gwendolyn Zapp's lab is developing a terrifying growth hormone called Compound 415-C. As she comes to the realization that things are getting out of hand at the lab, she decides to take it down to Earth and develop it down there instead. The Greens get ready to throw their party with Cricket dressed at a jester named "Trickor", though no one seems to get it, and Tilly dressed as Bill. Bill reveals that their pumpkins have not developed properly and are tiny, disappointing him.
Bill and Tilly go to deliver their produce to Big Tech where they run into Gwendolyn. She is actually excited to see that the pumpkins are tiny and shows them her lab and reveals the compound to them. With the compound, their produce can grow big and fresh in a matter of seconds. Bill turns down the offer, but Tilly begins to think on it and takes it secretly. Upon returning home, the party has already started and Tilly sneaks into the garden with the compound. True to Gwendolyn's word, the compound makes the pumpkins grow big an healthy.
Meanwhile, Remy is trying to calm Vasquez down as he cannot tell what is a prank and what is real and Cricket's "tricks" do not seem to have any real effect. Tilly takes Bill to show them their pumpkins and they happily take them inside. However, Benny notices that something is off about them which concerns Tilly. After falling for a prank set up by Cricket and Remy, they are suddenly attacked by a mutated pumpkin, but destroy it easily. Tilly asks for the boys help in trying to stop the party and destroy the pumpkins. When they try to tell everyone to leave, the pumpkins show up and begin capturing and possessing everyone, including Gloria who closed her café early that day.
The pumpkins kidnap Bill while Cricket, Tilly and Remy all hide. They manage to take out one of the pumpkins and free Vasquez who joins the children in their crusade to defeat the monsters. While Tilly goes to rescue Bill from the shed, Cricket, Remy and Vasquez try to free the others from the pumpkins who appear to be creating a tower of some kind. Tilly finds Bill who reveals what she did, only to be interrupted by a large pumpkin monster who escapes from the shed and unleashes small pumpkins that they must fight. Cricket is accidentally tossed out of the house and joins the fight while the pumpkins inside retake everyone and capture Remy and Vasquez.
The pumpkins create a giant radio tower of sorts that sends a message to all the pumpkins all over Big City and brings them all to life. With one final trick up their sleeve, Cricket distracts the big pumpkin and Tilly destroys it with the riding mower, causing all the pumpkins to rapidly die. With the city saved, Bill forgives Tilly and tells her that in order to be a good farmer she has to learn from her mistakes. Gwendolyn arrives after seeing the commotion on Mars, but leaves when she sees that it has been resolved. As she flies back to the planet, vines overtake it and it jump scares with Tilly's face on it shouting "Happy Halloween!"
- Chris Houghton as Cricket Green
- Marieve Herington as Tilly Green
- Bob Joles as Bill Green
- Artemis Pebdani as Gramma Alice
- Wendi McLendon-Covey as Nancy Green
- Zeno Robinson as Remy Remington
- Danny Trejo as Vasquez
- Cheri Oteri as Gwendolyn Zapp
- Anna Akana as Gloria Sato
- Luke Lowe as Benny
- Betsy Sodaro as Community Sue
- Andy Daly as Officer Keys
- John Early as Alexander
- Lamar Woods as Weezie
- Colton Dunn as Brett Eze
- Monica Ray as Kiki Kitashima
- Character costumes are:
- Cricket as Trickor the Jester
- Tilly as Bill
- Bill does not have a costume, but in the intro he is dressed as a pirate.
- Gramma Alice as a butcher
- Nancy as Freddy Kreuger
- Remy as a dinosaur
- Vasquez as a dinosuar
- Gloria as a cat like last year.
- Benny as a football
- Weezie as Geordi La Forge
- Kiki as Diamondbow
- Officer Keys as a prisoner
- Community Sue as a punk rocker
- Brett as a caveman
- Skids as a pirate
- Additionally two kids are dressed as Speed Racer and Gordon Freeman.
- This episode is revealed to take place one year after the events of "Blood Moon".
- Chronologically, this episode should have taken place before "Chipwrecked" when Big Coffee was standing and Gloria mentions she closed the café early, which is followed by "Big Resolution" when the café became vacant, but the Gloria + Green Café was seen instead of Big Coffee for an unknown reason, creating a plot hole in the timeline. Chris Houghton mocked this on his Tumblr page.
- The Greens own a dancing toy of the Monster Man from the Broken Karaoke segment of the same name.
- Not only is the intro another Halloween themed intro, but the credits also use the song "Monster Man" instead.
- Gloria is apparently already running her café successfully. Seeing as how this episode was produced to be released in time for the season, it is most likely that Gloria's travails in running her establishment will be expanded on in a later episode.
- Despite the fact that Kiki speaks in this episode, Monica Ray is only listed under Additional voices.
- According to Shane Houghton, this was the first episode of Season 3 to be finished, with all other Season 3 episodes unfinished at the time of the premiere.