The episode begins with Princess Bubblegum and Starchy, hovering over Gumbald's new city-state, Gumbaldia, taking pictures of his army. PB is frustrated and believes war to be the only revolution, much to Finn's disliking. As the Candy Kingdom prepares for war, Finn and Jake decide to confront Gumbald, to call off the war.
Finn and Jake arrive at Gumbaldia, but come across the Green Knight/Fern, whom fights them. However Aunt Lolly comes in to stop the fight. Lolly told Finn that she is not in favor the war and that Gumbald has gone mad. Lolly introducing Finn and Jake, but whispers in Gumbald's ear. Gumbald shows the brothers around the fortress, Finn then realizes how similar he and PB are. Gumbald shows Finn his giant cake robot, similar to the Gumball Guardians, as they stand on a high platform. The platform then collapsed and Gumbald fell, but Finn and Jake saved from the fall. Gumbald was happy that Finn saved him and began to think that Gumbaldia and the Candy Kingdom can coexist.
Finn and Jake were then having a joyful dinner with Gumbald, Lolly, and Chicle, in which Gumbald called off hostilities between the Candy Kingdom and Gumbaldia. Chicle then splashed Finn and Jake with a "celebration bucket" filled with some sort of "glitter juice", while telling the duo to give PB "a big hug." Finn and Jake begin to shake the juice off, splashing on Chicle. Chicle, horrified by what happened ran into the bathroom. Finn and Jake were confused but Lolly covered up what happened.
Finn and Jake then returned to Princess Bubblegum giving her the peace treaty. Bonnie was about to hug Finn, but noticed the way he and Jake smelled. Peppermint Butler then walked up to Finn and Jake and wiped them off with a towel. Peps was then transformed into a dumber, naked baby-like peppermint Butler. PB then realized that the glitter juice was Gumbald's dum dum solution and that he had attempted to have her subjected to it. Furious, Bonnie walked up to the tower, formally declaring war on Gumbaldia. Finn felt horrible about the entire outcome.
The Squirrel overheard all of this and ran to Gumbaldia, reporting that the war is back on. Gumbald then stated, that Lolly's plan (splashing Finn and Jake with Dum Dum Juice and have them hug Princess Bubblegum) had failed, despite it being a good plan. Chicle (who was splashed with Dum Dum Juice) reverted back to his old, dumber self, Crunchy then asks "What's a plan?" Gumbald then said it is time to unveil plan B, to his Legion of Candy Kingdom Haters, Ricardio, Bandit Princess, Samantha, Peace Master, Me-Mow, Pete Sassafras, Ash, Sir Slicer, Scorcher, the Green Knight, and a confused Ice King. Gumbald then says "It's Gum War."
- Candy People
- Ice King
- Green Knight/Fern
- Bandit Princess
- Peace Master
- Pete Sassafras
- Sir Slicer
- The Morrow
- Ricardio's body is reverted back into its original form, rather than his newer one appearing in "Lady & Peebles."
- This is the final episode to be 11 minutes in length
- This is also the final episode to use to normal Adventure Time theme song
- This is the also the final episode where Princess Bubblegum is seen wearing her classic dark pink gown.
- The ruins that Fern and Finn visited in "Three Buckets", and that Gumbald has been occupying since "The Wild Hunt", are now the central structure of Gumbaldia.
- Jake mentions the events of "Always BMO Closing" after Finn says they should fix the conflict.
- Finn and Jake mention the events of "Jake Suit" to Gumbald, Lolly, and Chicle.
- Many antagonists from past episodes appear.
- The Squirrel returns from "The Duke", "Princess Potluck", "Hot Diggity Doom", and "Normal Man."
- Ricardio returns from "Ricardio the Heart Guy" and "Lady & Peebles."
- Bandit Princess returns from "I Am a Sword."
- Samantha returns from "The Pit."
- The Peace Master returns from "Nemesis."
- Me-Mow returns from "Jake vs. Me-Mow" and "Angel Face."
- Pete Sassafras returns from "Candy Streets."
- Ash returns from "Memory of a Memory" and "Betty."
- Scorcher returns from "Hitman."
- Sir Slicer returns from "Blood Under the Skin."
- When Gumbald and Finn are on the lift, Gumbald ignores what Finn says and goes on about how Princess Bubblegum will be dead. The third time he says "dead", the lift fails. It's quite likely that "dead" was a signal/codeword for Lolly to cut the lift's rope.
- Chicle turns back into Crunchy due to the Dum Dum Juice. This fits in with his appearance in the future shown in "Graybles 1000+".
- Peppermint Butler gets splashed with Dum Dum Juice, thus turning him into stupider, baby-like peppermint, and quite possibly causing him to forget his identity.
- Gumbald has transformed the area around the temple he was seen inhabitng previously in "The Wild Hunt" and "Always BMO Closing", into a Candy City, known as Gumbaldia. It has many similarities to the Candy Kingdom and he seems to have citizens, whom he likely created.
- This episode was released early on the Cartoon Network app on March 9, 2018.