The episode opens with a flashback four years before the show begins. The Watterson family is in a rush to drive to the hospital to deliver Anais. Nicole is enduring physical and emotional stress as a result of going into labor, while Richard attempts to console her. In the back of the car are 8-year-old Gumball and 6-year-old Darwin fantasizing about how having a baby sister would be wonderful for them; one such example of an improvement to their lives would be having an extra playmate. Nicole is about to give birth very soon, so Richard needs to park, but since time is running short, he decides to drive directly through the hospital. The car then rushes into the emergency room, and when the vehicle exits from the other side, Anais had been born.
On the way back home, Gumball and Darwin are overcome with joy as they meet their newborn sister for the first time. Anais, at first, appears to be cheerful and innocent, but then pulls a sinister face and proceeds to throw the boys out of the car where they land in wet concrete.
Later, they return home and start wondering why Anais had suddenly become hostile as a nature documentary plays on television. The narrator discusses how newly hatched baby eagles would roll their unhatched siblings off the nest. Gumball remarks that babies are born innocent, yet the narrator continues with how baby sharks would attack each other before they were even born, much to the boys' horror. Darwin suggests that Anais may be scared, and that they should show her how much they love her.
The boys go upstairs to see their baby sister drawing a picture in her playpen. Anais shows them her drawing of their parents as the boys point to who is who in the picture. When they ask where they are, she points to the flowers; however, Anais soon makes clear that Gumball and Darwin are not the flowers, but rather their skeletons buried underneath the flowers.
Gumball and Darwin then propose a game of hide-and-seek, to which Anais agrees. In the backyard, the Watterson children play the game, with Gumball and Darwin doing the counting. When they uncover their eyes after they have finished counting, they somehow find themselves on the expressway, and they narrowly avoid getting run over by a truck.
Anais is in the process of tearing up her papers and toys when her brothers arrive back home. Gumball declares that she will "go back to where she came from," much to Darwin's shock. Darwin observes that she has vandalized her playpen by writing "NO ONE LOVES YOU -Gumball and Darwin" with surprisingly decent penmanship. Gumball proclaims that he would never write like that, hence Anais revises her handwriting with misspellings to replicate what would be Gumball's handwriting. Darwin questions what is going on as Anais rehearses her crying before successfully making herself do so. The boys realize that she had set up a trap, what with the torn up toys, vandalism on her playpen, and her loud crying. Before they could escape, they are caught by an angry Nicole and Richard, who are led to believe that the boys were mistreating their sister.
At the dining table, the boys deny being jealous of the new baby; Gumball proposes having another family adopt Anais. Nicole explains that the boys may no longer be the "babies of the house," but it does not mean that she or Richard would love them any less. While the parents and the boys have a group hug, Anais watches them from her playpen in the living room where she then declares war.
Gumball and Darwin are now in their bedroom saying that they are the problem, not their newborn sister; therefore, they start playing another game. At this point, 'Peek-a-boo' is what they are playing. On the first attempt, Anais is bored with the boys' effort to entertain her, and on the second attempt, the boys realize that a candle bound to fire extinguishers has replaced Anais, to which the bomb-like contraption explodes in their faces.
The war continues on. Such acts of war include Darwin getting trapped in his fishbowl with an anvil sitting on top of a pile of bricks and a piece of cardboard. At first, Darwin somehow believes he is going to drown; however, remembering he is a fish, begins to not care about his dilemma. Next, Gumball is attempting to take a bath when his sister turns up the water temperature to the point of a floating rubber duck visibly melting quickly, and before Gumball can enter the water, the heat turns the tub into a geyser and the water instantaneously evaporates. Then, Darwin is shown to be playing outside with a toy car and a doll; however, Gumball rushes to Darwin just in time to save him from being harmed by the rigged toy car, which explodes.
Later, Gumball and Darwin are eating cereal when they catch a glimpse of Anais staring at them with a sinister glare. This terrifies them, causing them to do a spit-take. Gumball asks Darwin what he thinks she could have done to their breakfast. Darwin states that even though the food has been untampered, it has enough sugar to do harm to one's arteries in a couple of spoonfuls. Overcome with anxiety, Gumball begins to hyperventilate, but Anais is quick to provide a paper bag for him to breathe into. Snatching the paper bag, Gumball is about to exhale into it when Darwin stops him and reminds him to think twice before trusting their baby sister. Upon further inspection, a swarm of bees emerge from inside of the bag and relentlessly sting the feline.
Gumball begins to cry, giving up on his attempts to befriend their sister, and when Darwin begins to think that there is nothing to be done in retaliation, the sight of Anais sucking on her own foot when she snaps out of her sinister demeanor leads to a critical reminder: Anais is still an infant.
Later that night, Anais is drawing when she turns around and sees an open box. Delighted, she crawls towards the box and enters just as Gumball releases the flap, trapping her inside. Gumball begins to boast about how she fell for his trap, laughs, and then the boys carry the box to a dog food factory, intending to pass off the infant as unlabeled meat; however, when the box is lifted, Anais falls out and remains in the crib unbeknownst to her older brothers and pulls her sinister face again.
The cardboard box is now sitting in the middle of the street in front of the boys' house as the two of them watch from inside. Gumball explains to Darwin that this is to cause Anais to start getting scared enough to supposedly "melt her heart a little", which technically counts as psychological torture. Darwin then points out that a trashman had come to the neighborhood street to collect that night's trash, the cardboard box being amongst the objects thrown into the back of the trash truck, much to the boys' horror.
Gumball and Darwin chase down the trash truck while dragging one another (quite literally) and taking turns fainting. The two of them then spot a conveyor belt that leads to a crusher with the box being sent towards it. Still assuming that Anais is in the box, Gumball hops onto the belt and sprints toward it. He manages to reach it and push it out of the way only for him to be crushed instead. After finding that he survived unscathed, he finds that the box is headed towards a grinder, but thanks to Darwin's control, it is diverted to another path.
Gumball finds himself on another conveyor belt after dropping from the hole created by Darwin, and notices a large circular saw in the middle of the path to slice garbage. Gumball runs towards the empty box and saves it from being sliced, almost getting sliced himself. After saving the box and managing to remain unharmed so far, he laments the oncoming pit of fire that awaits him, and feels remorse at his moral standards whilst falling into the flames before a mechanical claw descends to save him, which of course is operated by Darwin. After saving his brother, he drops the feline beside the pit, now on the outside.
Gumball and Darwin hug the box, apologizing to Anais (who they still think is inside), but they realize it was empty upon opening it. They look down from the edge of the pit and start fearing the worst when a sinister Anais sneaks up behind them. She intends to kill them by pushing the both of them into the inferno, but they turn around and are overcome with relief as they embrace their infant sister. Anais finally warms up to her brothers, evident by her returning her older brothers' love by hugging them. She then speaks her first words, "Gumball did it," alerting their angry parents to their presence whilst the infant laughs.
This is the third and final time Anais is seen as a baby. The first two were in "The Choices" and "The List."
This is the second time Gumball is almost killed at the junkyard; the first was in "The Hero" (although it is technically the first time seeing as this episode takes place four years before the rest of the show.)
Richard driving through the hospital is a reference to "The Money," when he flashes back to driving through the convenience store.
Gumball is wearing the same striped shirt as in "The Choices" and "The List."
When Gumball was thinking about protecting Anais from Kayvon, he referenced one of Homer Simpson's catchphrases "Why You Little!"
The long hair that Gumball has in the princesses fantasy is a reference to Rapunzel's long hair from the fairy tale Rapunzel, whereas Darwin's resembles that of Belle from Beauty and the Beast.
The faces that Gumball and Darwin make when they watch baby sharks eating each other are very similar to the face Enel makes in One Piece when he learned his powers were ineffective against Monkey D. Luffy, or the one Perona makes in her fight against Usopp for the same reason.
The scene where Gumball tries to make it out of the dump before getting burnt by the incinerator and is saved by Darwin operating a large clawed crane is similar to how Woody, Buzz, Jessie, Bullseye, Slinky, the Potato Heads, Hamm, and Rex escaped the incinerator in Toy Story 3.
Anais' quote "This is war. War does not determine who is right, only who is left!" is a direct reference to the quote made by philosopher Bertrand Russell.
Anais' painting might be a reference to Tokyo Disneyland's Haunted Mansion.
The nature documentary talks about baby eagles pushing their unhatched siblings out of the nest due to competition, though in reality only the common cuckoo is known to exhibit this behaviour, and even then towards birds of other species within whose nests the cuckoo's mother lays it. Although, bald eagle hatchlings are still naturally very competetive against each other, yet they do not try to kill their siblings.
Anais says her first sentence, "Gumball did it" on the same day she was born.
This episode contradicts the events that happened from "The Choices," where Anais rewrote her name correctly with Nicole and Richard in their current series appearance, even though Gumball and Darwin are still in their same younger selves.
Anais was able to draw Richard and Nicole in their current outfits despite the fact that Anais has only ever seen them in their old outfits the moment that she was born.
Daisy the Donkey can be seen in the kids' room even though a segment from "The World" revealed that Anais got Daisy for her birthday.
[The episode begins in a scene where the car, which the Wattersons ride in a setting four years before, is launched recklessly on the streets of Elmore; the screen is paused to say "FOUR YEARS AGO", then resumes. Richard is shown driving the car while perspiring, as pregnant Nicole breathes heavily to appease her pain]
Richard: Just close your eyes and breathe deeply. You can do this.
[Nicole, encouraged, responds by taking deep breaths]
Richard: [Hushed] It's only driving a car, it's only driving a—
Nicole: [Notices a car coming toward them, then steers the wheel] Watch out! I'm the one who needs help here! You said you read the baby books this time!
Richard: I did read them. But there was nothing about handling this level of stress in "The Ugly Duckling"!
Nicole: Not the books for babies, the books about babies!
Richard: Stop screaming at me. All you have to do right now is not have a baby. You do that every day! I'm just asking for a little sympathy here.
Nicole: How about some sympathy pains?! [Punches the airbag, which responds by suddenly expanding, leading her to struggle, then pass out]
Richard: There you go. Make yourself comfortable.
Gumball: I, for one, cannot wait to meet our new little sister.
Darwin: I know, right? It'll really improve our game of Knights and Princesses.
[The scene transitions to a clip of them playing Knights and Princesses; however, both of them are princesses on top of a castle, having no knight to save them. Clip ends]
Darwin: And having a sister will make us better listeners.
Gumball: Exactly. And having a sister will make us better listeners. Plus we'll look cool when we protect her from bullies.
[A hypothetical depiction of Anais being taken away her teddy bear from toddler apple plays]
Gumball: [Coming to kick him] Why, you little—
[The screen freezes]
Gumball: [In retrospective] Okay, maybe not.
[The screen transitions back to Gumball and Darwin]
Darwin: But at least she'll hook us up with her friends when the time comes for us to get married.
[A depiction of aged Gumball and Darwin plays as they are each married to babies, which are rocked back and forth by them; the screen freezes]
Gumball: I don't know, man. They'll always be a lot younger than us.
Darwin: But if we take good care of them, they can return the favor when we're old.
[A depiction of frail, old Gumball and Darwin plays, as the two babies are grown up, awkwardly rocking them back and forth]
Gumball: Oh, yeah.
Gumball: Well, either way, I can't wait to meet her.
Nicole: She's coming!
Gumball: I mean, I could wait a little.
Richard: Hold on, honey. We're almost there. I just have to park.
Nicole: No time!
Richard: We'll use the drive-through.
Nicole: There isn't a drive-through at the hospital!
[The car crashes through the emergency doors, and into one of the doctors]
[A miraculous birth follows]
[The car then crashes out of the visitor doors]
Richard: There is now.
Nicole: [Exhausted] Boys, say hello to your little sister. [Falls asleep]
[A stroller containing Anais is shown between Gumball and Darwin]
Gumball and Darwin: Anais!
Darwin: Aww, look at her.
Gumball: She's so sweet, she's given me [With teeth falling out] cavities. Um, dude I— I think you had a little accident.
[Darwin is shown in the midst of a puddle of pink, glowing substance]
Darwin: It's just my heart melting.
[Anais is shown innocently giggling; her face turns to a sinister countenance, as she pushes the boys out of the car into concrete]
Thinking Up a Strategy
[Gumball and Darwin enter the house with their heads in hardened concrete cubes; the television plays]
Narrator: [On TV] And here we witness the delicated first seconds in the life of a great bald eagle. But who would expect such a sweet chick to also be a natural born killer?
[An egg is shown that cracks for a newborn eagle chick]
Narrator: If sharing is caring, then this is the eagle that just don't care.
[The chick is shown pushing one of the other eggs out of the nest. The boys crash their concrete-covered heads to smash off the concrete]
Gumball: There's no way Anais would have pushed us out of the car on purpose. You know why? Because all babies are born innocent.
Narrator: And if you thought all babies were born innocent, check out these baby sharks eating each other before they were even born!
[Gumball and Darwin turn shocked]
Darwin: Wait. Maybe she did it because she was scared? So what do people do when someone's scared?
Gumball: Hmm. [Shaking Darwin] Pull yourself together! You're being hysterical!
Darwin: Okay, I meant what do morally well-balanced people do when they're scared? We show her how much we love her.
Gumball: [Shaking Darwin] I love you and value your companionship!
[Gumball gently caresses Darwin]
Darwin: That's better. See? [With a baby's face] Happy baby!
Struggles of Being Anais' Brothers
[Anais is shown drawing with crayons in her crib; Gumball and Darwin enter]
Darwin: Hey, Anais. What's that you're drawing?
[Anais shows her picture of only the parents]
Gumball: Oh. Very good. [Pointing to Nicole] Is that Mommy?
Darwin: And Mister Daddy?
Gumball: And where are we?
[Anais points to the flowers]
Gumball: Oh, we're the flowers?
Anais: Mnh-mnh. [Expands the drawing, showing Gumball and Darwin drawn as buried skeletons]
Darwin: Oh. Right. Er, let's play a game. You want to play a game?
[Anais laughs in agreement. The scene then cuts to the children in the yard]
Gumball: Okay, this one is called hide and seek. We close our eyes and count, and you hide. Ready?
Gumball and Darwin: [Covering their eyes] One, two, three, four, five, six, seven, ten! Ready or not, here we come!
[The kids are revealed to set on the road with an upcoming truck; they scream and duck. Darwin's soul is so scared it escapes his body and floats upwards]
Darwin: Hey! [Grabs and pulls to set himself back] Where are you going?! That was terrifying.
Gumball: Yeah, well, at least your soul was going upwards.
[Scene switches back to Anais playing in her crib at the house; she rips off the chest of her stuffed teddy bear]
Gumball: All right, I've had enough of you. You're going right back to where you came from.
[Darwin realizes and gasps]
Darwin: Hey, what's that? [Points to a message written by Anais]
Gumball: "No one loves you. Signed, Gumball and Darwin." [Scoffs] I would never write something like that.
[Anais erases the message and rewrites it accordingly to the way Gumball would write it]
Gumball: "No won luvs u." Well, yeah, that's more like it.
Darwin: What is going on here?
Anais: [Clears throat, soft cry] Mnh-mnh. [Soft cry] Mnh-mnh. [Clears throat, gasping cry] Mm-hmm. [Hits her head with a maraca, then cries]
Gumball and Darwin: It's a trap! [Try to run out]
[Nicole and Richard rush in to the bedroom, blocking them; they realize the framed situation and express anger. The family is shown at the dinnertable]
Gumball: Listen, I'm not jealous. It's just, you know how adopting Darwin really brightened everyone's lives? Well, don't you think it's time we gave that gift of happiness to another family? And by "that gift of happiness," I mean Anais. And by "another family," I mean a pack of scavenging hyenas.
Nicole: [Sighs] Look, I understand. You're no longer the babies of the house, and that's a big adjustment. It was difficult for your father, as well.
[Richard whimpers with dilated pupils]
Nicole: But just because there's a new baby in the house doesn't mean I'll love you any less.
Gumball: So you mean love multiplies?
Nicole: No, it divides. But I'll take the difference from your dad's portion and hope our marriage survives until you go to college.
Richard: Mm-hmm. Wait, what?
Nicole: Now, let's hug.
[All hug, except for Anais, who is still in the crib, wearing the recurring demon-like expression]
Declaration of a Baby War
Anais: [Speaks gibberish; translates to:] "This is war. War does not determine who is right, only who is left." [Pounds on toy, which then plays "Rock-a-Bye Baby," which Anais enjoys very much]
[Gumball and Darwin are shown in the bedroom, looking over Anais in the crib]
Darwin: Maybe, Mrs. Mom was right. Anais isn't the problem. We are. Come on, let's play with her.
Gumball and Darwin: Peek-a-boo. [Make funny faces]
[Anais is shown bored]
Gumball: Hmm. Let's try it with funnier faces.
Gumball and Darwin: Peek-a-boo. [Make funnier faces]
[Anais is shown still cross]
Gumball: Oh, come on.
Gumball and Darwin: Peek-aaaaaaaaa…
[The scene reveals that in the crib four cans of explosive gas are lit with the candle, which explodes the second floor of the house. Gumball and Darwin's bodies, except their face portions, smother into ashes and fall]
[Scene switches to Darwin sleeping in his bowl. When he gets up, his head bumps against a board weighed down by some bricks and an anvil. Darwin screams in need for oxygen and passes out]
Darwin: Huh? [Realizes he is a fish] Mm.
[Scene switches to Gumball preparing himself for a bath. Anais controls the temperature of the bathtub water to be extremely hot, and as Gumball is about to step in, all of the water in the bathtub evaporates. Scene then switches to Darwin playing with his toy car]
Darwin: I'm gonna go for a drive. [Inserts action figure]
Gumball: Darwin, no! [Pushes him away]
[The toy car explodes; Gumball and Darwin realize that Anais is the mastermind. Scene switches to the boys eating cereal, but notice that Anais, next to them, is wearing the demon-like expression once again. They spit out their cereal]
Gumball: What has she done to our cereal?
Darwin: [Grabs box] Mm, it looks okay.
Gumball: Why's she doing the face, then?
Darwin: [Examines box again, then gasps] There's enough sugar in here to clog your arteries in a couple of spoonfuls.
Gumball: [Hyperventilating] I can't take this anymore! I'm getting anxiety attacks. [Grabs paper bag from Anais' hand] Oh, thank you.
[Darwin pulls his hand away from the bag, as Anais wears the face; the bag trurns out to be filled with bees which sting Gumball's face several times]
Gumball: [Swapping then away] Get away! [Face is filled with swollen purple bumps; cries]
Darwin: [Petting Gumball] There, there. You know what they say. What doesn't kill you—
Gumball: Will try again later! We have to counter-attack.
Darwin: But how? She's smarter than us.
Anais: [Notices her feet and screams in gibberish; translated: ] "OMG! I got feet!" [Sucks her own foot]
Gumball: Yeah, she might be terrifyingly intelligent for her age, but she's still her age.
[Scene switches to Anais drawing with crayons. She notices a box trap set up by Gumball and Darwin next to her and crawls inside]
Gumball: [Closes trap] Ha! You fool! You fell into our trap. You lose. Hear our superior laughter.
[Gumball and Darwin pinch their throats, performing their superior laughter]
Gumball: [Carries box, which does not carry Anais, leaving her in the crib] And now we're gonna send you as unlabelled meat to the dog-food factory.
[Anais pulls the recurring face; scene switches to the box laid on the middle of the road, as Gumball and Darwin watch]
Darwin: So no one's actually coming to collect her?
Gumball: 'Course not. We're just gonna leave her outside until she's stewed long enough for her cold, dark heart to melt a little.
Darwin: Oh my gosh, that's horrible.
Gumball: It's fine. We're only giving her a little scare to assert our authority.
Darwin: No, I meant [Pointing] that's horrible.
[The Dolphin Man, as a garbage worker, dumps the box into his dump truck. Gumball and Darwin react in extreme horror; Darwin is then shown chasing the truck, dragging fainted Gumball]
Gumball: [Gasps] Oh, yeah, sorry. It's your turn to pass out now.
[Darwin passes out; Gumball drags him. Gumball and Darwin follow the truck into the dump]
Gumball: Anais?! Where are you?!
Darwin: [Regains consciousness] There! Look!
[The scene then focuses on the conveyor belt leading products to be smashed by a crusher, in which the box lays on; Darwin passes out again in reaction, then is grabbed by Gumball]
Gumball: No. We have to save her. [Runs up to the box on the conveyor belt and pushes the box away from being crushed by the crusher; then, gets crushed by the crusher into a "2D" shape; then, regains his "three-dimensionality"] Oh, ha. I guess there is an advantage to being two-D. [Gasps]
[The scene reveals that the box is about to be crushed by a series of grinders; Gumball runs up in vain]
[The box drops in a hole, which happens to be activated by Darwin in the control room, who then tries to recreate a thumbs up]
Gumball: Good work, buddy! [Drops onto another conveyor belt]
[The conveyor belt is revealed to lead items to be sliced in the middle by a circular saw. Gumball runs up and lifts the box above himself; as the circular saw is supposedly about to slice his crotch, he raises said crotch enough so that he survives without a scar, resulting in a sigh. Gumball's legs split, due to the conveyor belt splitting into two separate lanes]
Gumball: Oh, come on.
[The conveyor belts are then shown leading toward a incinerator]
Gumball: I really wish Mom didn't raise me so well, 'cause this deserves a much stronger cuss word than fiddlesti-i-i-cks! [Begins to fall toward the fire]
[Darwin, in the control room, controls a mechnical claw to seize Gumball; he gasps in response, as the mechanical claw drops him onto an area in front of the incinerator. He then focuses toward the box, which seems to them that Anais is in there]
Gumball: [Crying] Anais, we're so sorry.
Darwin: [Jumps in, crying] We're so, so sorry.
Gumball: So sorry. I'm sorry.
[Both open the box, which evidently appears empty]
Gumball: Huh? Anais, where are you?!
Darwin: Anais, where are you?!
Gumball: Anais! Anais, where are you?!
[As Gumball and Darwin look for Anais in the incinerator, sobbing, Anais, with her demon-like face, walks up behind them]
Anais: [Speaking gibberish, translated as:] "Peek-a-bye; Time to fly the nest!" [Fails to push them]
Gumball and Darwin: [Noticing Anais] Anais! [Hug her]
Darwin: We thought you were gone!
Gumball: We— we— we thought we'd lost you.
[Anais struggles to escape the pressure from Gumball and Darwin's hug; however, she notices their affection and hugs back]
Gumball: [Gasps] Oh, my gosh, her first words!
Gumball: Yes, yes, "Gumball." It's me. She's trying to say my name.
Gumball and Darwin: Yes?
Anais: Gumball did it.
[Gumball and Darwin look behind to see infuriated Richard and Nicole, who both groan. Anais simply giggles. Episode ends]