Karai and a squad of her Foot soldiers are jumping from rooftop to rooftop in the vast city. Karai then tells them to stay very alert, for the Turtles have been sighted in the area that they're in a few times before. Coincidentally, they hear the Turtles not that long after down in an alley way below and take note of the fact that they are fighting strange, ubiquitous alien robots. At that moment, Leo happens to look up, and he spots Karai observing him. He smirks at her and then bravely defeats all of the remaining Kraang, showing off his skills to the kunoichi (since he has a secret crush on her, though not as obvious as Donnie to April's), under the notion that he can possibly impress her; even slightly. However, Raphael takes notice of his brother's awkward behavior (and actually spots Karai as well), and mentions it to Leo without actually saying Karai's respectable name; And this leaves Mikey and Donnie to greatly wonder what the two are chatting about.
At The Shredder's lair, Baxter Stockman is nearly finished in creating an apparatus for Xever (we realize that this is exactly what he was enlisted for in "Mousers Attack!") that allows his mutated form to breathe, walk, fight and do many other things on land. However, just when Xever takes on the long-awaited pleasure of standing up, Stockman's creation (and control device) is quick to malfunction, and he is unable to properly get control of Xever's mechanical legs from that point on Dogpound thinks that this is simply too hilarious, and he immediately starts laughing at the likes of Xever. A now impatient Shredder witnesses Stockman's incompetence as well, however, and threatens Stockman with the removal of his legs if the operation of fixing the suit is not quickly renewed and begun. Karai then enters the scene from above, and tells him that she had just witnessed the Turtles fighting a bunch of 'slimy aliens' in robot bodies, and that their could be prudence in investigating the creatures and Xever and Bradford becoming hideous, anthropomorphic monsters, but The Shredder only dismisses this idea of her's, and instead reminds her of his ongoing vendetta against Hamato Yoshi and how they absolutely need to construct and complete their revenge for what the man had done to "them", raising some questions. He then tells her to stay focused on her one, true mission. She puts on her mask and agrees to this with a sinister look.
Back at the lair, Raph confronts Leo about him defeating the rest of The Kraang as just a means of 'impressing' Karai. Leo says that he was just trying to show her how formidable they are, but Raph has little to no credence in this. Raph then tries to convince Leo countless times, that she can't and should never be trusted in any way, shape, or form, describing her as a "black hearted scoundrel". Lovestruck by her, Leo bluntly ignores him. Instead, this ends up escalating into a brawl just when Splinter enters the scene, asking what this is about. Leo and Raph both lie and say that it's nothing really, and Raph angrily walks out, hitting Leo in the shoulder. Elsewhere, in the living room, April tells a curious Mikey and Donnie about a school project that she's doing. It involves sending a sample of each student's DNA to a place called the World Wide Genome Project, and they will send you back a report on a piece of paper that displays tons of info about your ancestors, in turn.
The next night, Leo waits for Karai to show up on a particular rooftop, hoping to talk with her about certain matters. She shows up and immediately tries to ask him about The Kraang, but Leo refuses to tell her anything about the dangerous robots, but only advises her to stay away from them. They then proceed to duel, with Leo still trying to convince Karai that she has somewhat of a good side within her and he also voices his belief that she is simply looking for a convenient way out of the Foot Clan. However, she flatly rebuffs this and responds by only snickering at him and sarcastically calling him 'adorable'. He's briefly caught off guard by this statement of her's, but quickly recovers and continues to fight with her. Finally, as a conclusive statement, he tells her that, if she dares to try to harm his brothers, he will go after her. She verbally acknowledges this and the two part ways. Oblivious to him, she holds ulterior motives.
At April's school during the following day, April walks in, only to find a woman named Ms. Campbell standing above the small stairway there. She repeatedly tells April to come with her so that she may receive her DNA test results. However, April suspects something's wrong due to her rather robotic voice, and she then tries to escape, but Ms. Campbell grabs her arm and pulls her backwards. April runs, manages to elude her attacker and hide in a broom closet, and immediately texts the Turtles for help. The Turtles soon arrive at the school and engage in a big fight with Ms. Campbell (who is actually a robot that can shoot missiles out of her elbows). After cutting off her face and spraying water on her, they quickly find out that she was a Kraang droid. They then think that the Kraang might've already hacked into the Worldwide Genome Project's network, and they decide to go investigate, telling April to head back to the lair where it's much more safe.
That night, they quickly locate the building and break into it, completely unaware that an ever curious Karai is following them once again. While inside, they quickly realize that the Kraang are the ones running the World Wide Genome Project, and have been managing to collect DNA from numerous plants and animals for an unknown purpose. Just then, it is revealed that Raph found Karai when he is then seen grabbing her. She and Raph then begin fighting, mostly for the heck of it. Leo tries to break them up, but he accidentally stumbles backwards in doing so and presses a button that summons The Kraang. They then start fighting all of the robots and Leo yet again tries to convince Raph that Karai does have some virtuous intentions like themselves (when she is shown slicing just a few of the robots in half), but Raph realistically chooses to ignore him. When the Turtles are eventually trapped in a corner because of the Kraang's very high level of Tech, Karai recklessly, yet intentionally presses a button that combines all of the DNA samples (which creates a grotesque monster, despite both the Turtles' and Kraangs' warnings for her not to do so), she quickly picks up a slightly broken Kraang exo-suit, and rudely abandons our four heroes. Leo is heartbroken to finally see Karai's true colors, he realizes that Raphael was right all along. With all of his brothers and The Kraang utterly defeated by the Mutant, Leo angrily faces it by himself now. He quickly discombobulates it and then uses both of his Katanas to deflect one of the blasts from it's laser eyes and it subsequently blows up into smithereens, causing the entire building to collapse in exchange.
At the lair, Leo finally tells all of his disappointed brothers, April, and Splinter about his true sentiments for Karai. He admits that he had feelings for Karai and he delusions-ally thought that she could team up with them and do something good for a change. Donnie and Mikey are shocked and disappointed, April and Raph tried to warn him all this while, and Splinter tells him that .
In response to this, Splinter tells him that Leo is not the only first one to be foolish after having a crush on a girl, stating that Karai is an expert on deception, and Leo should treat her as an enemy instead of vice versa. He also advises him to not get infatuated with her anymore. Leo thanks him for his understanding, but Splinter injures Leo's foot with his cane as an apparent form of punishment. Before Leo goes into his room to go to bed, Raph comes up to him and says that he's glad that he came to his senses, upon which Leo apologizes for not listening to him very much - and Raph accepts it. Raph actually tells him that he understands why he was partly attracted to her, but now he believes that Leo is totally over it. However, Leo then looks down with a somewhat dejected expression, hinting that he may indeed still have some feelings for Karai.
Back at The Shredder's lair, Karai interrupts the recurring chaos of Fishface's malfunctioning legs and delivers the Kraang exo-suit right to Stockman. The Shredder once again continues in his rant and begins to tell her that he has little interest in The Kraang whatsoever, but the villain is then quick to change his mind when a contented Stockman makes a claim. The functionality of this Tech is very similar to if not the exact same type of neural-transmission interface that he has relentlessly been trying to develop for weeks on end (by himself). The Shredder, seeing that this may mark the beginning of a new era, comes right up behind his adoptive daughter, places his two hands on her shoulders and tells her that she has done very well. She bears a conceited evil smirk.
Ms. Campbell is the first female robot/Kraang droid to be introduced in the series, as well as the first to have a separate identity, the second being Kraang Prime
April's school is shown for the first time.
The motto of April's school appears on a sign outside the building and on the floor in front of the entry. It reads "Aut disce aut discede", which is Latin for "Either learn or leave."
Donatello uses the naginata blade in his staff during the fight with Ms. Campbell. That is the first time he has been shown using the blade successfully in combat.
Shredder's threat to remove Stockman's legs may be a nod to his first punishment of the scientist's failure back in the 2003 series.
When trying to name the super mutant, writer Kenny Byerly decided to call him "Justin" after one of the production assistants, Justin Nix. 
When Karai tells Shredder about seeing the Turtles fighting alien robots, she first describes them as "some guys in suits". However, the Kraang-droids were not wearing suits, or any kind of human disguise, when Karai saw the Turtles fighting them.
Xever is listed as "Fishface" in the end credits, but he does not receive that nickname until the following episode.
In the beginning of the episode it retained the small mouthed animation and in the later in the episode they had the big mouthed animation like in the earlier episodes, especially in the fight with Ms. Campbell.
When Leo say "Let's get out of here" when the world wide genome project is about to be destroyed, he has no swords. However when the turtles are watching the building being destroyed Leo has his swords on his back like he had never dropped them.
When the Turtles first came across the Kraang droid that was attacking April, they managed to have a short conversation before the droid started attacking. But they first thought the droid was a human, and the Turtles really should know better than to be seen by humans, let alone talk around them.
"Raphael: Nice try, Octo Punk! (referring to Justin) Michelangelo: No, no, call him Octo Eyeball Jelly Bug! (realizing the name doesn't work) Ugh. Let's just call him Justin."
"Raphael: So, guys, we all fans of Karai yet? Donatello: I don't know who she is but I know I HATE her!"
"Donatello: Did you guys just get a mass text from April? (others nod their heads and reply yes) Does yours also say she's being attacked by an old lady?"
"Kraang: Highly undesirable outcome. (referring to Karai about to push the button)"
"Kraang: The ones who are not authorized by the authority of Kraang to exist in this place, will now be destroyed by Kraang in this place. (Kraang referring to the turtles and Karai)"
"Raphael:Hey look, Leo! The Kraang are on our side now! Leo: Save it! (Raph and Leo after Karai abandons them)"
"Karai: You're adorable! Stupid, but adorable! (Says while fighting Leo) Leo:Really? You think I'm-- AH!"
"Raphael':(fighting and talking to Leo) You really think Mikey and Donnie wouldn't understand? (Pauses) You really think Donnie wouldn't understand?"
"Michelangelo':(upon seeing cat symbol, screams like a girl)"
"Kraang: When this fight is concluded, the ones called the turtles will be beaten by the Kraang."
"Splinter: Leonardo, you are not the only person or turtle to fool yourself in front of a girl. Michelangelo:What about Donnie? (Donnie hits him)"
"Splinter: Deception is the ninja's most powerful weapon. And Karai appears to be a master of it.
Leo:Thank you, Sensei. I'm glad you're not mad. Splinter: Who says I'm not mad? (pokes staff in Leo's foot and Leo screams)"
"Leo:Alright, guys. It's time to put Old Mother Hubbard back in her cupboard (referring to Ms. Campbell). (Others groan.) Raphael: Dude. It literally hurts to listen to you sometimes."
"Raphael: (holding Karai) Bet you think you're pretty slick? Karai: (flips Raph) I have my moments."
"Karai: I like your brother, Leo. (slices Kraang droids) He's almost as entertaining as you."
"Raphael :Oh, when this is over I'll show you how entertaining I can be."
" Justin: Meow!
Michelangelo: Aw! He's so cute! (Justin expands his snake-like neck, stretches out his jellyfish-looking eyes and spreads out his piscine fins that slightly resemble a cobra hood)"
" Karai: (to the Foot soldiers) "The Turtles have been spotted in this neighborhood. So stay alert for any sign of them.""
" Leo: "Raph's right, it is my fault." Justin: "ROAR!" Leo: "AAHH!!" (he charges at Justin as he avoids the electric blasts from his jellyfish eyes. He then hits the mutant a couple of times, but is unable to knock him out when he hits his isopod shell. Justin picks up Leo with his tentacle, then Leo uses his katanas as he slides down, and splats Justin on the ground. Justin recovers) "Hey, Justin, this ends now!" (Justin blasts electricity, but they hit Leo's katanas. The turtle uses his katanas as conductors as they smash the machine, setting Justin on fire as he flees)
Michelangelo: "HA! Take that, Justin!""
"Michelangelo: "So..." Donatello: (to Leo) "We're thinking somebody should start talking!"
(Leo becomes sad as the scene cuts to the lair) Le: "I should have told you about Karai sooner, but I really thought there was a chance she would be good, and... I guess I... sort of... liked her. Go ahead, laugh."
Michelangelo:"Dude, I can't believe you trusted her." Donatello: "I can't believe you didn't trust us enough to tell us." Leo: "I was wrong, I'm really sorry." April: "I tried to warn him." Raphael: "You too, huh?""