(The episode begins in the Candy Kingdom, the scene changes to Finn, Fionna, Jake, Lumpy Space Princess and Lady Rainicorn running through the streets with Candy Zombies swarming them at every side, Finn flings one away as it jumps on him, they burst through the front gate of Princess Bubblegum's Castle)
Finn: Hurry, Lady!
(Lady rushes through the gate and they close the gate and latch it)
Finn: (Breathing hard) It's happening again.
PrincessB: That's right, Finn.
Princess Bubblegum: The zombie infection has spread across the kingdom once again, ...and once again, it's all my fault.
(Princess Bubblegum's Lab)
Princess Bubblegum: (Narrating) I was testing a sample of the zombie flesh I had saved when Cinnamon Bun came into the lab. He said he was hungry.
Cinnamon Bun: I'm hungry.
Princess Bubblegum: Not now, Cinnamon Bun. I'm busy. (Turns her back on Cinnamon Bun to work with some chemicals)
Princess Bubblegum: (Narrating) And that's when I made my mistake. I should have paid more attention to that poor fool. (Cinnamon Bun starts messing with the zombie flesh and eats it) The Candy Zombie flesh he ingested was highly contagious. (CB groans and falls to floor behind the counter and being groaning violently)
Princess Bubblegum: Cinnamon Bun? Where did you... (Zombie Cinnamon Bun lunges from behind the counter at Princess Bubblegum) EEEEHHHHH!!!
Cinnamon Bun: Sugar!
Princess Bubblegum: I escaped, but I wasn't able to stop Cinnamon Bun from infecting the rest of the kingdom. The good news is I still have all my notes for making the antidote formula.
Finn: Oh, sweet!
Princess Bubblegum: Let's board up the windows then we can get started.
(A zombie bursts through a window and bites Princess Bubblegum on the neck and drags her out)
(Finn runs to the window and grabs Princess Bubblegum's arms)
Princess Bubblegum: Don't worry, Finn. You have the notes to my formula. Just let Science do the work. Science... is...MURRAHH (Trying to say Science is My Rat!!!!!!). (Turns full zombie)
Finn: NOOO!!!! NO! NO! NO! NO!
(Zombie PB is pulled out)
Finn: She's gone, she's gone, SHE'S GONE! It's all my fault!
Fionna: Don't blame yourself, Finn. You did all you could.
Lumpy Space Princess: Aw, nah, I am not getting eaten by zombies tonight. (Starts to board up the windows, when zombies begin to peek through and Lumpy Space Princess smashes them with a hammer) Get the lump outta here!!! Ahh! Ahh!
Jake: These notes make no sense. It's all gobbledy-gak.
(Lumpy Space Princess takes the notes and Finn takes some and give them to Jake and Lady Rainicorn)
Finn: Alright, we'll each make our own version of the formula. One of us is bound to get it right.
(A montage begins where the group makes there formula)
(A candy corn lab rat on the table begins to move frantically)
Fionna: Hey, Princess Bubblegum trained her rat to dance. Neat.
(Montage continues and ends)
Finn: (Laughs) Done.
Lumpy Space Princess: Done!
Jake & Lady: Done!/("Done!")
Finn: Bubblegum, I'm comin' for you!!!
(They go to the boarded window where zombies are peeking through)
Finn: Mine first.
(Finn pours his formula on a zombie's arm and it promptly grows wings; Finn and Jake gasp; it bites zombie Pineapple Guy, who grows wings and they both bite another zombie that grows wings and they fly away)
Winged Zombies: Sugar!
(They fly around and two of them crash into the castle)
(Scene cuts to tops of a building where Starchy is)
Starchy: Oh, my, that's a lot of zombies down there. Starchy's glad he's up here. (Starts to sing and dance happily; a winged zombie swoops down and grabs him) Dang it!
(Winged zombie dive bombs Starchy into the boarded window breaking it)
Fionna: Let's get out of here!
Finn: Stairs! (They all run upstairs to the top room of a tower)
Finn: Jake, try yours and Lady's next!
Lumpy Space Princess: Move outta the way! My formula is going to cure the zombies because I made the prettiest formula.
(Lumpy Space Princess dumps her formula out of a window on the zombies, who all grow huge red lips)
Lumpy Space Princess: Oh. My. Glob. Look at those luscious lips. I gotta go lick up the rest of that formula! Aaaaaaah! (Runs out of the tower and outside) My formula! (Pushes her way through the zombie horde) Formula! (Begins splashing the formula on her face) Oh, my Glob. Yes, I'm gonna look so hot! So freakin' hot! (Her lips begins to swell and she laughs) Yeah!
Finn: LSP, look out!
(The horde begins to swarm around her)
Lumpy Space Princess: Huh. I know you want this body, but you can't have it! You can't have it! (They swarm her and bite her turning her into a winged zombie, she flies up and presses her faces against the tower window)
Finn & Jake: LSP!
Finn: Dang it, Jake. We only got two formulas left. Try yours and Lady's.
(They pour it out the window on the zombies)
Jake: Let's hope this works.
(The zombies grow buff, they all fly up and smash their way into the tower.)
Fionna: I'm the last hope. C'mon...
(A zombie grows to be as tall as the castle, and lets out Godzilla's roar. Another zombie grows, this one letting out Gigan's roar. The two start fighting and destroying the town, as the Gumball Guardians come to life and engage the "Kaijuzombies". Meanwhile, the group starts running)
Finn: Wh-... where now?!
Fionna: We can barricade ourselves in the lab!
(They run into the lab and shut the door on the rampaging zombies)
Finn: Did anyone get bit?
Fionna: I think we're good. That door is made out of candy steel.
(Zombie Mr. Candy Cane comes out of a locker on the wall, Finn screams)
Fionna: What's the matter? (Sees the zombie and screams)
(Zombie Mr. Candy Cane heads towards Lady, but Jake uses his arm to push him back into locker and puts it against the door and puts a flowerpot on top of it)
Finn: Jake! Did it get 'cha?
Jake: I think I'm okay. It's just a little bite.
(The little bite starts to spread across his whole arm, Jake squeals. He stretches his arm, which begins to move on it's own, away from him as its spreads)
Jake: It's all good sweety. I can stretch forever, well kinda. There is a limit to how far I can stretch. Hehehehe...(To Finn, under his breath) Hey, let's hurry up with that antidote, huh, pal? (The plague spreads up his arm as Jake runs and continues stretching his arms) Whooa...
Finn: Okay, let's see here...(Looks at Princess Bubblegum's notes)
Jake: (Running) You should try one of them books. Over there by the lab rat.
Finn: Ha! Yeah, okay. (Runs overs to the books and opens one) Yes! This book has a glossary of symbols.
Fionna: Oh, that'll work!
Jake: (Running) That's great, buddy.
(The lab rat taps on the glass and jumps against it)
Finn: Fi, I think this little guy has serious dance fever.
(Jake is tired and gasping, he sees the "Sciencey Shower" in the wall and closes himself in it; Lady comes near the shower)
Jake: Don't come near me, sweety! (Gasps) Oh, man, I'm outta shape. I think I should just stay in here, ya know. Just in case. Ya oh.
(The plague goes up Jake's arms and he stretches his arm filling the shower)
Jake: Hurry, dude!
Finn: I am! Okay, Jake's probably going turn into a zombie, but that's okay. Me and Fionna just have to figure out this formula.
(Jake's arm retracts and reveals he is now a zombie)
Finn: Hang on, Lady! I'll have the antidote soon, but whatever you do, just don't let him out. He may look like the Jake that once loved you, but he's just a zombie!
Fionna: OK, we now know that the disease affects non-Candy People. This is bad.
(Lady looks at zombie Jake)
Lady: 아니야. 얘는 날 사랑해. ("No. He loves me.") (Lady lets him out, he cuddles her face and bites her)
Finn: Hey, Lady... (Screams)
(Lady is now a zombie, Finn and Fionna grab the cart with their equipment runs and gets the lab rat cage and put it on the cart, at this point the Candy Zombie horde breaks through the door, while a whole section of the lab is smashed by "Taffyzilla", who roars, then rushes back into combat; while the zombies release zombie Mr. Candy Cane from the locker. Finn and Fionna rush their cart into the Sciencey Shower and close themselves in, but accidentally drops the Symbols book outside)
Finn: The book!
(The zombies begin to crack the shower's glass, Finn looks around nervously)
Finn: (Sighs) Sorry everybody. Sorry, LSP, PB, Jake, LR, peepee poopoo doodoo.
Fionna: Looks like we're gonna die together.
(Finn sighs and looks at the lab rat)
Finn: You know, it's funny; I don't even know your name.
(The lab rat goes over to a label on the side of the cage that says " Science THX 11-38)
Finn: Yeah? What is it, girl? (The lab rat points at the label) "Sci... ence". Your name is 'Science'? Could it be?
PB: Just let Science do the work. Science... is...MYYRAAAT.
(Finn takes Science out of the cage and puts her on the cart, she looks at the notes and brings Finn and Fionna ingredients and they make the antidote)
Finn: Here goes nothing.
(Finn pours a few drops of the formula on Jake from over the glass, he returns to normal)
Jake: You did it! I huh, uh... (See the zombies around him who swarm him and turn him back into a zombie)
(Finn and Fionna look at Science who just shrugs, the zombies begin to break the the glass, Finn and Fionna gasp and Science looks nervous)
Finn: Don't worry, Science. I got a disgusting idea. (Pour the antidote over himself and Fionna, who gets the idea, and the zombies break through the shower and begin to bite Finn)
Finn and Fionna: OH, MY GLOB!!!
(Scene goes to black and returns as sunset is over the Candy Kingdom the next day; everyone is back to normal)
Jake: Sorry about biting you, sugar.
Lady: (Hugs Jake) 난 네가 깨물어 주는 게 좋아. ("I wanted you to bite me.")
Jake: (Laughs nervously and blushes) Oh.
Princess Bubblegum: And so the Royal Day of Apologizing has come to an end. (Princess Bubblegum takes a medal from a Banana Guard) And now I shall present the Royal Medal of Heroic Bravery. Finn and Fionna the Humans.
Fionna: That is us.
Princess Bubblegum: Would you please move out of the way?
(Finn and Fionna move, revealing Science)
Princess Bubblegum: Science the Rat, you have served your kingdom well. (Puts medal on Science) Citizens of Candy Kingdom, rejoice!
Princess Bubblegum: Rejoice!
Princess Bubblegum: Rejoice!
Princess Bubblegum: Rejoi-
Random Candy Person: WE GET IT! JUST SHUT UP!
(The camera goes to Science and the episode ends)