[It all started with Shredder's lair in the rainy night. Inside, there is Karai. The girl was thinking about what Leo had said to her in a flashback.]
Leo: Karai, don't do this. Splinter he's your father. Your true father. Hamato Yoshi.
[End of flashback.]
Shredder: What is it that troubles you, Karai?
Karai: I want to know the truth. The truth about my mother. And Splinter.
Shredder: You know the truth, my daughter. Hamato Yoshi took your mother away.
Tigerclaw: I have returned.
[Tigerclaw arrives, but now wearing an eyepatch and a torn ear.]
Karai: [Shocked.] How? You were eaten by a giant alien worm.
Tigerclaw: And you believed such a thing could contain my hate? My hate is what kept me going. As I tore my way out of the belly of the Kraathatrogon. As I battled through the armies of the Kraang across alien worlds that would drive lesser men mad. And finally, back here, back to my enemies. I would have my revenge against Splinter, against his hideous reptiles, and against those who trapped me in that wretched worm's belly.
Shredder: I will grant you this wish.
Karai: What? It's because of him that Splinter and the Turtles are still alive in the first place.
Shredder: Karai, you will go with Tigerclaw. Destroy Splinter and the Turtles at any cost.
[Tigerclaw and Karai start a hunt on the turtles.]
[In Murakami's restaurant, turtles start their training.]
Mikey: I've put up with you guys for a long time, but this is about to get real!
Raph: You don't want this kind of pain, Mikey.
Donnie: Big talk for someone with such a limited vocabulary, Raph.
[Raph shoves Donnie away by putting his hand on his brother's face.]
Leo: Are you sure you're ready?
Raph: Are you kidding me? I was born ready.
Leo: Okay, Mr. Murakami.
Murakami: One pizza Gyoza, coming up.
[Raphael, Donatello and Michelangelo have bug eyes, get their tongues out and they're drooling over seeing pizza Gyoza. Mr. Murakami throws the Gyoza to the turtles, they're fighting each other for these as they pin each other to the ground, pizza Gyoza falls on top of Mikey. Michelangelo closes his eyes and opens his mouth, beleiving that he will win the pizza Gyoza, but to his shock, sword appears and it catches pizza Gyoza. It is revealed that Leo catched the Gyoza.]
Leo: Ha, I thought I'd play after all.
[Leo eats the pizza Gyoza and gives his brothers mocking smile, this leads his brothers to get angry.]
Raph: What happened to Mr. "I'm too broody for this game"?
Leo: Mmm, these things are really good.
Murakami: My restaurant was never that popular until invented these for you.
[Mr. Murakami hands them full plate of Pizza Gyoza. They have a heart shaped eyes, cut to the turtles hands taking away pizza Gyoza. The turtles eating their pizza Gyoza. While eating, Donatello notices Leonardo is glancing to the window, depressed about Karai.]
Donnie: He's still brooding.
Raph: He's thinking about her. About Karai.
Leo: Master Splinter is her father. How could she still want to be with the Shredder?
Mikey: You have to have faith, Leo. Her entire life was shown to be a lie. This is a challenge to everything she knows. The truth will set her free. Just give her the time she needs to accept who she is.
Donnie: Right. Look, Leo, she'll come around.
Raph: Yeah, well, personally, I hope she doesn't. I don't trust her, not for one second.
Donnie: You're right, Raph. You shouldn't trust anyone.
[Meanwhile, up on the rooftops...]
Tigerclaw: Having a hard time keeping up, girl?
Karai: I was taking it easy on you since you're working with only one eye and no tail.
Tigerclaw: You think you're clever? You're a fool.
Karai: I'm the fool? You've faced the Turtles in battle before and lost. What exactly is your grand plan for revenge here?
Tigerclaw: To destroy warriors such as these, you don't strike at their limbs, you go for their heart.
Karai: And what does an overgrown cat know of the heart?
Tigerclaw: Why do you think the Shredder sent you with me?
Karai: [She thinks about it for a moment before her eyes widen in realisation and horror.] Because I know them. I know the places they go. I know their weakness. Their friends April o'Neil and Casey Jones.
Tigerclaw: The riders of the worm. They will all pay for what they did to me.
[Back at Murakami-san's Noodle Shop...]
Murakami: Hello? Is somebody there? Leonardo?
Karai: Not quite. The Turtles.
Murakami: I don't know what you're talking about.
Karai: Lying will only make this worse. Leonardo, Raphael, Michelangelo, and Donatello. Where do they live?
Murakami: I don't know. Please, please.
Karai: There is no honor in this
Tigerclaw: I didn't come here for honor.
Mikey: Guys, stop!
Leo: What is it, Mikey?
Mikey: I feel like we're forgetting something. Something important. Something something the fate of the world could depend on. It's right on the tip of my tongue.
Donnie: The Kraang?
Leo: The Foot clan?
Raph: The Rat King?
Mikey: No. Wait! I remember. My doggy bag. The leftover Gyoza are back at Mr. Murakami's. We have to go back. Fate of the world!
Donnie: What happened?
Mikey: Mr. Murakami! Mr. Murakami, it's me, Mikey. Are you okay?
Murakami: They came looking for you. They wanted to know where you lived. But I didn't know. They asked about your friends. To my shame, I told them everything I knew.
Raph: Who did this?
Murakami: The girl and the growling man.
Leo: Tiger Claw is back. And he's going after April and Casey.
Donnie: We have to get to April And Casey, you know, time permitting.
Raph: The girl has got to be Karai, Leo. I told you-
Leo: Not now, Raph.
Donnie: April's not answering her T-phone. She always answers.
Leo: We'll split up. Me and Donnie will go to April's place, you and Mikey get to the ice rink and warn Casey.
Donnie: Why wouldn't she answer her phone?
April: Best movie ever! The part where the Captain is cornered by the monster, and it's all slobber and fangs and goo, and then boom, that explosion knocked them out of orbit and and they're falling into the star and and and--
Casey: I just don't get why our date had a third wheel attached to it.
Irma: Hello? I'm right here.
Casey: That's the problem.
April: Who said anything about this being a-
Casey: What is it?
April: We're being followed.
Casey: All right, whatever it is, we split up and lead it away from the third wheel here. Plan?
Irma: Guys, am I missing something? Well, that's just great.
Casey: Yes! Coast is clear. Casey Jones can't be caught. Aww, nuts. Come on, tiger dude. Let's see what you.... got? You know what? On second thought, I don't need to see what you've got.
Kirby: She's not answering. She always answers.
Donnie: That's what I said!
Leo: Kirby, you said she went to the movies. That's where we start.
April: You want to do this, Karai? Fine. But I'm warning you, I've been training with Master Splinter big time, and I'm ready to kick your butt.
Karai: I didn't come to fight. I came to talk.
April: Oh, well I've been trained in that too.
Casey: Whoa! You know, part of me always wanted to fight a man eating tiger. Know any real ones?
Tigerclaw: Do you think this is a game?
Casey: Whoa! Yeah, keep away from one eyed freaks. Or we could play a game of crush the cat. Later. Yeah! Woo! If it wasn't for the fact that I'm gonna die, this would be so cool.
Karai: All my life, I was raised to believe that the Shredder was my father. That Splinter was the enemy. So when Leo told me that Splinter was my true father, I couldn't accept it. But then I began to have doubts about Shredder's honor.
April: Doubts about the evil leader of the evil ninja clan? Really?
Karai: Yes, even now, the Shredder has sent Tigerclaw to destroy the Turtles. He's trying to use me to set a trap for them. But I can't. Even if it means betraying Shredder.
Casey: Taste exploding puck! Okay, catman dude, you wanna do this? Let's do this. Ah! Whoa!
Tigerclaw: You will pay for what you did to me, the suffering you caused, the pain I endured.
Casey: You're not still mad about the whole worm thing, are you?
Raph: Casey? Casey? Casey, answer me! Something's wrong, Mikey. What are we gonna do?
Mikey: I know exactly what to do. We can use our phones to triangulate the position of Casey's T-phone by bouncing the locator signal off the satellite.
Raph: That's actually a good idea.
Mikey: It's like we're in some kind of alternate universe or something. You can also track pizza delivery guys that way. Booyakasha!
Donnie: There's April. Come on! Get away from her.
April: Leo, Donnie, wait. You have to listen to what she has to say.
Karai: I believe you, Leonardo. I believe that Splinter is my true father.
April: I believe that she believes you.
Donnie: I believe April.
Leo: This this is great. I knew you'd come around. We'll take you to the lair to see Master Splinter.
Donnie: Whew. Raph's not gonna believe this.
[In the lair, Raph is outraged.]
Raph: [Furious.] I don't believe this! What have you guys done?!
Raph: What world do you live in that it's okay to bring the princess of the foot clan to out secret lair?
Leo: What happened to Casey?
Raph: Tigerclaw threw him off a building. And you just brought his partner in crime home for dinner.
Karai: Shredder lied to me! I didn't know.
Raph: Did you know that I'm about to stick this sai right up your-
Leo: Raph, no! She understands now. She gets it.
Donnie: She knows the truth, Raph. Everything's gonna be fine.
Leo: Will you just listen?
Raph: I've heard enough from you and your girlfriend. She's probably leading the Shredder here right now.
Splinter: Enough! Miwa.
Splinter: Come with me.
[Karai follows Splinter into the dojo.]
Splinter: I retain very little from my old life, but this I will never let go my daughter.
Karai: I...I can't believe it. You're telling the truth. All these years, the Shredder has been lying to me.
Leo: Wait, you can't believe it? I thought you did believe it. If you didn't believe it, why did you come down here?
Karai: [realizing] Father.... What have I done?
Tigerclaw: Reptiles. Where are you? Underground, in the sewers.
Splinter: You had to see with your own eyes. You had to learn the truth for yourself.
Karai: You knew. You knew I was lying.
Splinter: No doubt the Shredder's forces are on their way.
Donnie: What was that last part?
Karai: Tigerclaw is tracking me.
Raph: I told you!
Karai: There's no time to argue. I have to get out of here. I can- I can lead Tiger Claw away.
Splinter: Go, take Karai and watch over her. I will stay with April and attend to Casey. You are who you choose to be, not what others make you.
Raph: Some of us choose to be right all the time.
Leo: Will you just go?
April: Do you think he's gonna be okay?
Casey: April Why did you have to bring Irma again? She's so nasty.
Raph: Well, princess? You got us into this. Where to?
Karai: I... I don't know.
Leo: Everyone, stop! I know exactly where to go.
Donnie: I feel scared.
Tigerclaw: I can't smell you, but I can hear you. Show yourselves! They're stalking me. Are you afraid to face me? Ah! Are you afraid to fight me? Let us finish this.
Tigerclaw: Karai, would you like the honor of finishing him?
Karai: I have no honor. But that's about to change.
Tigerclaw: If you value her life, do not take another step. Just as I thought.
Leo: No! Come on, we have to-
Donnie: Wow. I think his shell was knocked loose. We have to get him back to Master Splinter.
Leo: [Worried.] Karai.
Raph: I still don't trust her.
Leo: Are you kidding? She saved us.
Raph: The Shredder raised her. Daddy's probably welcoming her home right now.
[Back in the Shredder's lair...]
Tigerclaw: She has betrayed you, Master Shredder. She fought alongside the Turtles.
Karai: Tell me the truth! Splinter is my father, isn't he?
Shredder: Yes. Hamato Yoshi is your true father.
[Karai looks down, incredibly dumbstruck and flabbergasted about being lied by Shredder. She realizes that she really is the daughter of Hamato Yoshi as Shredder walks over to Tigerclaw.]￼
Shredder: Tigerclaw, take her away.
[As a punishment for betreyal, Karai is been thrown out in the cage at the dungeon.]
Karai: No. No! No! What are you doing? NOOO!
[Karai cries out in despair as the episode ends.]