The episode begins with Gumball and Darwin in the school bus going to school. Gumball asks Darwin what he wants to do after school but Darwin cannot make a decision and says that he is bad at making choices. This leads to a flashback where Darwin is unable to decide on a signature when he is given a card to sign for Teri's birthday. Gumball thinks that making decisions is easy and tells him to use his brain. Darwin says that it is busy (telling his body to function), so Gumball says that he can go on like that or he could let him make the decision for him. Darwin hesitates to answer so Gumball says he has decided.
One week later, Gumball thought the week went well but Darwin says all his decisions have gone wrong. Gumball gets off the bus and Darwin says he will not take his advice anymore. Gumball tells Darwin to get off the bus but Darwin says no as he is no longer taking Gumball's advice. Darwin then gets squashed between the bus door and then says from now on he will get his advice from somebody else.
In the cafeteria, Darwin decides who to pick for his mentor. He does not think Tobias or Banana Joe would work well, and he is not even sure who Gregor is, but then he sees Alan teaching kids why they should eat vegetables and picks him. Alan accepts the role of his mentor and the two of them go and make good decisions. Carrie is better after Darwin apologizes to Carrie for a bad date. Principal Brown says that Darwin has made the best solar system diorama he has seen all year. The hexagon lady thanks Darwin for calling the pest control and Darwin explain how it was Alan's decision for Darwin to call them rather than trying to save the dog himself. The Donut Cop thanks Darwin for calling him so he was able to catch Sal Left Thumb and Darwin says it was Alan's idea. Teri thanks Darwin for the best meringue she has ever had but she then asks him if he is okay as Darwin is floating, has a high-pitched voice and thicker eyelashes, and squashes like a balloon when she hugs him. Darwin says he is fine and has never felt better.
Gumball appears angry because Darwin has decided to choose Alan as his mentor. Darwin asks him to join them but Gumball says why he should do so. Darwin is confused and Gumball says that he is "turning into him [Alan]" and then "deflates" Darwin. Darwin says he is making better decisions but Gumball says that he is just doing what Alan says. Alan then whispers to Darwin what he should say and Darwin says what Alan told him to. When he realises what is happening, he gets sad and runs away. Gumball thinks the conversation well but Alan disagrees. Alan goes off to find him but Gumball thinks he is going in the wrong direction. Gumball bumps into to Teri and accidentally tastes the meringues, admitting that they are good.
Darwin is in the mall trying to make a good decision and Jared tells him he should get a burger for half off. Darwin is happy that he had made a decision himself but then is sad when he realises he is just doing what Jared told him to do. He goes to the burger stand and asks for a burger. Larry asks which burger he would like and the teapot tells Darwin he should get the "slaw-crime," so Darwin agrees and gets it. Then, Larry asks if he wants to go large and Darwin is unsure. Other people in the line fight other what what size he should get which causes Marvin to fall and make all the payphones get knocked down squashing Banana Barbara and making her land in Coach's mouth which made her fall down and break the escalator. Darwin stands there hesitating on what to do. Gumball and Alan find Darwin and Alan tells Darwin to leave but Gumball tells him to stay. However, he unintentionally takes Gumball's advice as the Donut Cop locks the exit. At one point, Tony gets pushed onto Siciliana and eats one of her pepperonis which makes Quattro angry enough to punch him. Tony's back hits a pipe, breaking it. The pipe bursts, spraying water everywhere, and floods the center of the mall. Alan tells Darwin to get to higher ground whilst Gumball says to sing a song. A boat comes up to Darwin and one of its crew members tells him to get on, but then Banana Bob tells Darwin to get on an arcade machine that is on fire and sinking. Gumball and Alan argue again about what he should go on. Gumball tells Alan to "tie a knot in it" meaning to stop giving bad advice but then Alan goes to the pipe and blocks it with his balloon knot. Alan starts filling up with water but overfills so Gumball tries to push the water back into the pipe but his leg gets stuck.
Darwin then tries to help. He asks Larry how to stop the pipe from flooding and he says that Darwin needs to go in the basement. Darwin thanks him and swims away but Larry asks him if he wants to go large or not. Darwin is in the basement and is given a choice to go left or right. He goes left, but hits a dead end so he ends up going right. He finds a door but it is locked. He then finds an axe in a glass case and uses the glass case to knock the padlock off the locked door. Inside, there is a wheel that Darwin struggles with but then eventually turns which stops the mall from flooding. Gumball gets trapped within Alan's folds but Alan then realies the water had stopped and Gumball puts his thumbs up. Darwin then pulls Gumball out of Alan and Gumball congratulates Darwin for making a good decision. Gumball and Alan argue about how to remove the water from the center of the mall but Darwin goes down and moves the plug in the water fountain that keeps the water in and all the water drains. Then, Darwin goes back up and tells them what he had done. Alan then asks how he can revert to his normal size and Gumball says he can do this himself. He pulls out his claw and pops Alan, despite his victim's protests. Water shoots out of the mall and knocks the cops over.
Gumball, Darwin and Alan go and get ice cream. Gumball orders three chocolate ice-creams, but Darwin decides he wants a strawberry ice-cream instead. Larry says they are out of strawberry ice-creams, so Darwin just goes with a chocolate ice-cream, ending the episode.
Gumball: Well, you can either go on like that, or you can let me make all your decisions for you!
Gumball: It's decided, then!
One Week Later
[One week later, the brothers are on the school bus again]
Gumball: It's going pretty well, don't you think?
Darwin: Really? [Shown with his head on fire; Gumball blows out the flame] You said it would be better for the environment if I chewed on sugar cubes instead of gum!
[Flashback to a group of firefighters attempting to pry a crazed Darwin from his desk. Some students watch frightened]
Darwin: I can taste sound!
Gumball: What about your date with Carrie?
Darwin: Rather than express my feelings, you said I'd seem more cool and mysterious if I answered every question with a question!
[Flashback to Darwin and Carrie at the cinema. Darwin holds an uneaten hot dog]
Carrie: Aren't you gonna eat that?
Darwin: Aren't you?
Carrie: Um, no! You know I can't eat stuff!
Darwin: Do I?
Carrie: Well, you should! I'm your girlfriend!
Darwin: Are you?
[Carrie moves the hot dog and uses it to slap Darwin's face. Flashback ends]
Darwin: And the perfume I got Teri for her birthday? I wanted to pack it with bubble wrap, but you said...
[Flashback to Darwin, Masami, Alan, and Bobert celebrating Teri's birthday.]
Darwin, Masami, Alan, and Bobert: Happy birthday to you, happy birthday to you...
[Teri opens her gift from Darwin. It is a perfume bottle, packaged in paper shreds. Teri inspects the paper closely and gasps in horror]
Darwin, Masami, Alan, and Bobert: Happy birthday, dear Te... ri...
Teri: Uncle Brian? [Screams]
[Flashback ends to everyone exiting the bus]
Gumball: Well, I was only trying to help.
Darwin: Well, I've had it with your advice, and I'm not gonna listen to you anymore!
Gumball: Uh, dude, I suggest you get off the bus.
Gumball: Before the doors close.
Darwin: [With his face smooshed between the doors] Okay, but from now on, I'm gonna get my advice from someone else!
[In the cafeteria, Darwin tries to find his personal mentor]
Darwin: [Thinking to himself] Hmm... who to choose?
Tobias: [Walking with Masami and Carmen] Ladies, the equator called! It wants his hotness back... from me... because I'm hot... [Points to Carmen] for you.... [Points to Masami] or you.
Masami: Tobias, you don't have enough respect for girls!
Tobias: [Leaning on Carmen] Ha, sure I do!
Masami: You're literally leaning on Carmen.
[Upon realization, Tobias screams in pain and jerks his arm away. He pulls one of Carmen's spines out of his arm.]
Darwin: [To himself] Mmm, too slimy. What about Joe?
Banana Joe: Hey, everybody! Watch this!
[He throws his peel into the ground and, with a running start, slides on it like a sled. He crashes into the trash can and falls in. Rocky notices his peel on the ground and throws it in. He empties the trash and replaces the trashcan liner.]
Banana Joe: [Inside the trash bag] Ta-da...
Darwin: [To himself] Nah, too... weird.
Gregor: Hey! Want to check out the new milkshake place after school? You know your boy Gregor is all about his milkshakes!
Darwin: [To himself] Who even is that guy? [Walks in the other direction] Wait!
[Suddenly he sees the perfect mentor: Alan. Sparkles appear around him and high-pitched music plays, which turns out to be sung by Darwin]
Darwin: Of course! Alan!
[Alan is sitting with a group of daycare kids]
Little Timmy: Why can't I eat chocolates instead of vegetables?
Alan: Because, sweet child, chocolate is fun for a treat! But vegetables are the... [Shoving an eggplant up his know] cornerstone of a healthy diet! [Panting] And are very important! And you need to [keeps shoving] make sure you eat at least five a day! [The eggplant finally goes through; chuckles] Delicious!
Peggy: If you were talking while you were eating, then where did the—
Darwin: Hi, Alan!
Alan: How can I help, Darwin?
Darwin: Alan, you seem to have it all figured out. Could you help me make the right decisions?
Alan: Of course! I'd be delighted to!
Peggy: [Holds out a pineapple] Isn't fruit one of your five-a-day too?
Alan: [Chuckles nervously, pushing her away] Anyway, Darwin, let's get out there and start making some better decisions!
[A few days later, in the hall. Darwin is walking with Carrie.]
Carrie: It was so refreshing, you just straight-up apologized to me.
[Alan passes by and winks at Darwin. He winks back, with a thumbs-up.]
Carrie: Normally, you'd try some kind of harebrained scheme to win my heart back. You're definitely making better decisions.
[They pass by Leslie and Carmen, who both smile at him]
Carrie: And I think everyone's starting to notice—
[The scene cuts to Principal Brown evaluating Darwin and Alan's science fair project]
Nigel Brown: Uranus, and Neptune. Well, that's the best solar system diorama I've seen all year. Well done, Darwin. You boys remind me of myself when I was a—
[The scene cuts to the hexagon lady with her dog, who was just saved by Darwin and Alan]
Hexagon lady: Disgusting vile sewer rat! But little Wilfred chases anything. I'm just glad you saved him.
Darwin: Thanks, Mrs. Lady! Alan advised me to call the relevant authorities rather than go into the drain myself! He's the real hero!
Hexagon lady: I never said you were a hero. But still, I'm very grateful. All I can say to you is—
[Cut to the Donut Cop arresting Sal Left Thumb]
Donut Sheriff: Eat it, greaseball! [To Darwin] Son, we couldn't have done it without you.
Darwin: Thank you, officer! Rather than trying to take on the criminal myself with an elaborate scheme and accidentally joining his gang in the process, Alan told me to just call you!
Donut Sheriff: I didn't ask, but I'm sure the mayor will invite you to City Hall so you can both be—
[Cut to Teri holding a meringue]
Teri: Whipped... to perfection! Thank you, Darwin! This is the tastiest meringue I've ever had!
[She hugs him, causing him to stretch like a balloon.]
Teri: You okay? You don't seem yourself.
Darwin: [High-pitched voice] I'm fine! [Revealed to hover slightly above the ground] In fact, I've never been better! See you later!
[He and Alan float over to Gumball.]
Gumball: Well, looky who's made a decision about who's going to make their decisions!
Darwin: [High-pitched voice] Hello, Gumball! Won't you join us?
Gumball: Really? Join Head Zeppelin and his airhead puppet?
Darwin: What do you mean?
Gumball: Come on, look at you! You're turning into him! [Lets out Darwin's air, sending him on the ground] And I don't even wanna know how you got inflated in the first place.
Darwin: [Normal voice] But I'm making good decisions now!
Gumball: No, dude! You're just doing whatever he says!
Darwin: That's not true!
Alan: [Whispers to Darwin] I'm making all of my own decisions.
Darwin: I'm making all of my own decisions!
Alan: [Whispers to Darwin] All on my own, without any help from anyone else.
Darwin: All on my own, without— [Gasps] You're right! I'll never be my own person until I start making decisions for myself! [Runs off crying]
Gumball: Huh. That went pretty well, don't you think?
Alan: Uh, no! He ran off crying!
Gumball: Well, like I always say, you gotta break them down to build 'em back up again. Then, you break 'em down again, and then, you build 'em up again! Then, down again, then up again, then it's down, down, up, up, down, up, then all the way up, and then a little bit down and then you're done!
Alan: That sound like a cheat code for being a terrible friend. Come on. We better go find him! [Floats off]
Gumball: Oh, you would go that way, wouldn't you? Well, I say we should go this way-
[Gumball walks off the other way but collides with Teri. Her meringue flies into the air and splatters on them both.]
Gumball: Ugh! [Tastes some meringue] Darn it. They are good meringues, though.
[Darwin is at the mall]
Darwin: Okay. I can do this. Just make a decision to do something, and stick to it!
[Jared waves a Joyful Burger flyer in his face]
Jared: Hey, kid! Why not go pick up a burger? It's half price with this flyer!
Darwin: [Takes the flyer] Yes. Yes I will! There! I made a decision to do exactly... what that guy... told me. Ugh.
[He gets in line for the burger stand and hands his flyer to Larry]
Darwin: One burger, please.
Larry: Sure! Which one?
[Muriel, who is in line behind Darwin, whispers to him]
Muriel: Get the slaw crime. It's on promotion!
Darwin: Uh, okay. One slaw crime, please.
Larry: Excellent choice, sir! Oh, one more thing— [Dramatically zooms in] would you like to go large?
[Larry's words echo inside Darwin's head. He imagines himself falling through a void]
Larry: Hello? Hello?
[In reality, Darwin is just writhing on the ground with his eyes closed.]
Larry: Hello? Kid, which is it?
Pantsbully: Oh, c'mon, kid! Just go large!
Gary: No! Go small!
Harold: I say go medium!
[Harold stamps his foot, causing Jeff to ram into Muriel.]
Muriel: Hey, don't push!
[She pushes Jeff back. Everyone in line falls over, causing Marvin to knock over three call boxes. One of them falls on Banana Barbara, who shoots out of her peel, landing in Coach's mouth, causing her to get stuck at the bottom of the escalator. Darwin watches as a huge brawl breaks loose throughout the entire mall. Gumball and Alan find him.]
Gumball: There he is!
Alan: He's in trouble! Quick, Darwin! Get to the exit!
Gumball: No, Darwin, stay! Establish dominance now! The riot can smell fear!
[A police car pulls over. The Donut Cop assesses the scene for a few frantic seconds, then padlocks the doors.]
French Fry Cop: You're locking the doors, Chief?
Donut Sheriff: Best way to deal with rioters? Seal them in, and let them get it all out of their system.
[Back in the mall, Hank and George watch Felicity and Billy get into a tussle with the drum kit guy.]
Hank: Hey, look! Those people down there are jostling!
George: Kinda looks to me like they're fighting.
Hank: I said they're jostling!
[He slaps Hank into Tony, who falls on Siciliana. Her cheese and a pepperoni slice get stuck on his face. He takes the pepperoni off and eats it.]
Tony: Mm-hm! Pepperoni!
Quattro: Why, you!
[He punches Tony in the face, causing him to fly across the room and slam into the piping. The pipe breaks, and water starts jetting out and filling the entire room.]
Darwin: Oh no! What do I do?
Alan: Climb up to higher ground!
Gumball: No, sing a song! That usually seems to wrap things up! [Singing] Wintertime is a time for bells—
Alan: That's not even a song about the situation!
[A boat with three sailors inside pulls up to Darwin.]
Sailor: Get in, kid! There's room for one more!
Sailor: We have a spare life preserver!
Sailor: In exactly your size!
[Banana Bob passes by, using a burning arcade game as a raft.]
Banana Bob: No! Hop on this arcade machine! It's on fire! And, it's sinking!
Alan: Really?! Obviously, take the one that's an actual boat!
Gumball: But what if it gets boring on there? Get on the arcade machine, dude!
Alan: I think it's time we do something! The water's getting higher!
Gumball: You know what? I'm tired of all your advice. Why don't you just tie a knot in it?
[Alan looks at the pipe and has an idea]
Alan: Of course!
Gumball: That is not what I meant!
[He attaches his knot to the pipe, collecting all the water. He rapidly starts inflating and sagging due to all the weight]
Alan: There's too much water! I can't hold it all in!
Gumball: I know! If I run into you hard enough, it'll force the water back up into the pipe!
Alan: I'm not sure that's a good id—
[Gumball runs into Alan but only bounces off of him, hitting the wall and passing out. Alan, who is still inflating, is about to entrap him]
Alan: Gumball! Wake up! I can't stop!
[Gumball wakes up and realizes his foot is stuck under Alan. Neither of them are able to move.]
Gumball and Alan: Help! Help!
[Darwin, still in the water, hears them shouting for help.]
Darwin: Gumball! I've got to do something! [Notices Larry, riding the Joyful Burger stand] Larry! How do I stop the water?
Larry: There's a crank in the basement!
Darwin: Thanks! [Dives down]
Larry: [Holds up burger] Wait a minute, do you want to go large or not?!
Darwin Hatches a Plan
[Darwin swims down to the basement, but gets stuck at two diverging hallways. Meanwhile, Alan can barely hold any more water]
Alan: Sorry, Gumball, I thought this would make things better!
Gumball: Well, you did always have an inflated opinion of yourself. [Chuckles and grunts]
[Back in the basement, Darwin goes left but stops]
Darwin: Dead end.
[He continues right and finds the main water cut off valve, which is locked. He thinks for a moment, and then sees an axe in a glass box reading "BREAK IN CASE OF EMERGENCY." Darwin smashes the entire box against the lock, eventually breaking it and going inside. He starts turning the valve, but it gets stuck. While Gumball gets completely covered by Alan, after some struggle, Darwin gets the valve to start turning, shutting off the water ]
Alan: It... it stopped!
Gumball: [Completely covered by Alan] Yay.
[Darwin finds them, reaches inside Alan, and pulls out Gumball]
Gumball: Huh, ever thought about being a vet?
Darwin: No, a plumber! I turned off the water supply, and it was all my idea!
Gumball: Nice work, buddy.
Alan: But the mall is still flooded!
Gumball: Okay, well I think we should soak it up with as much rice and dehydrated fruit as you can find.
Alan: No! You should find a call box, and alert the relevant authorities!
Gumball: Ugh. You would say that, you—Hey, where's Darwin?
[Darwin swims to the bottom of the mall fountain, finds the drain, and opens it. All the water slowly drains out, making a loud noise. The noise is then revealed to have come from Leonard, slurping a soda.]
Leonard Daniels: What?
Darwin: I just pulled out the plug!
Gumball: Yeah, I guess that would work too.
Alan: But what about me?
Gumball: Let me do this one. [Nears Alan and extends his claw]
Alan: No, no, no, no, no—
[All the water shoots out, breaking through the doors and drenching the two cops outside.]
French Fry Cop: Chief, I can't feel my legs!
Donut Sheriff: And I feel like I've been dunked!
Three Chocolates, Please!
[Some time later, Gumball, Darwin, and Alan walk to the ice cream truck. Alan is completely stretched out]
Gumball: Well, at least Darwin is making his own decisions now.
Alan: Yeah, and I'm sure I'll be able to work off all the loose skin in no time!
Larry: What can I get you boys?
Gumball: Three ice creams with chocolate sauce, please.
Darwin: Wait! Make that two chocolate, and one with strawberry.