(Open up on the backyard. Isabella, Buford, Baljeet, Perry, Phineas, and Ferb are looking at what looks like a mountain of some sort.)
Phineas: Okay, gang. Today, we're gonna tie a legendary knot.
Buford: Woah woah woah! We're just startin'?! No—no intro, nothin'?! Just gettin' right into it?
Phineas: Yep, we're just doin' the knot.
Buford: Wait, how can we do something not?
Phineas: No, it's "knot" spelled with a "k".
Buford: I didn't think it was spelled with a "k".
Phineas: No. It's "knot".....spelled with a "k".
Buford: I don't understand your pauses.
Phineas: Well, lemme start over. Today, we're gonna reproduce the Gordian Knot.
Buford: Well, why didn't you say so in the first place?
Isabella: I've heard of that, but I can't remember the story.
Buford: I got this. Back in the day where men wore miniskirts...wiggle wiggle wiggle...wiggle wiggle wiggle...

(Flashback. In this flashback, the role of Alexander the Great will be played by Buford van Stomm.)
Buford: (voiceover) ...Alexander the Great was vacationing in Gordium, when he came upon a celebrated oxcart that was tied to a post using a knot that was so complicated, it was impossible to untie. So he just sliced it in half in one bold stroke.
(End flashback)

Buford: A simple solution to a complicated problem, hence the phrase, "Cutting the Gordian Knot."
Isabella: I've never heard that phrase!
Baljeet: That is new to me.
Buford: Trust me, it's a thing.
Phineas: So, we'll tie these ropes around our waists, and follow this blueprint to recreate it, then it's up to us to figure out how to get loose. That'll make us the second people to tie the Gordian Knot, but the first people to untie it!
Baljeet: What if we cannot untie it?
Phineas: (tying his rope around his waist) No problem. Our mom was always really good with knots. There was this one time when Candace—
(record scratch)
Candace: (leaning against the door) Hey! I thought we weren't going to bring up the clothesline incident ever again!
Phineas: Oh, right. Anyway, would you mind getting Mom if we get stuck in the ginormous Gordian Knot we're making?
Candace: When it gets big and weird, I'll go get Mom.
Phineas: Excellent! Does everyone have their ropes tied? Alright, lessee, Isabella and Buford, make two loops where you're standing. Great! You're good to start climbing. Baljeet, turn twice counterclockwise and then dive in five loops from the bottom. Then Ferb and I will do this and this and this, and we'll join you inside.
Ferb: Shall we?
Phineas: Absolutely. Let's go, bro! Baljeet and Ferb, twist to the right and wiggle towards the top. Hey, where's Perry?

(Cut to Perry somewhere around the house. He puts on his fedora and expects something to happen. Nothing happens. So he shrugs and gets a shovel labeled "Analog Lair Entrance". He begins digging down to his lair. Cut to the lair. Some dirt falls from above into Agent P's chair and Agent P follows.)
Major Monogram: Morning, Agent P! Seems that Dr. Doofenshmirtz has been hitting every all-you-can-eat buffet in town, which can't be good! If anything were to happen to Doofenshmirtz, we would have to make some drastic cuts over here! (looking aside) Especially in the non-essential personnel department. (Perry starts to vacuum all the dirt off the chair.) Good luck, Agent P. Oh, don't worry about the mess, uh, Carl will take care of it.
Carl: (off screen) I guess that makes me essential, huh?!
Major Monogram: Don't get cocky, Carl.

(Cut back to the Flynn-Fletcher house. The doorbell is heard ringing.)
Jeremy: Hey, Candace.
(Cut to the front door. Candace answered the door and Jeremy is in his Mr. Slushy Dawg uniform carrying a safe.)
Candace: Hi, Jeremy. What a nice surprise! (sees the safe) Ooh, what's that?
Jeremy: Oh, it's an old mini safe of mine that I found in the back of my closet. I've had it for ages, but I haven't used it in so long that I forgot the combination. I thought your brothers could open it. I figured that's a "safe" bet. Heh heh!
Candace: So what's in it?
Jeremy: That's the thing. I don't remember.
Candace: Maybe it's a rare baseball card.
Jeremy: No, I sold all those a long time ago.
Candace: Um, could it be your favorite toy car from when you were a kid?
Jeremy: No, I traded that for this safe.
Candace: Well, maybe it's something cute, like your baby teeth.
Jeremy: Nope. Definitely not. I still got those. (He lifts his upper lip to reveal his baby teeth stuck in his gums.)
Candace: Ew. I mean, cute!
Jeremy: Yeah, the Tooth Fairy never visited me when I was a kid. (pause) Anyway...could you give this to your brothers? I gotta rush to work.
Candace: (takes the safe) Sure. I'll give it to them as soon as they finish their Ferbian Knot. Don't ask.
Jeremy: (leaves) See ya later, alligator!
Candace: In a while, crocodile!
(Stacy comes to the door.)
Stacy: You guys have got to work on your pet names for each other. So what's in the safe?
Candace: I dunno. But it's not baby teeth.

(Cut to backyard where the mountain is now in the shape of a sphere.)
(Song: "Quirky Worky Song" (Jazz Waltz Version))
Phineas: (off screen) Okay, everybody. Two twists to the left and we should all see daylight.
Isabella: (coming out of the knot) Well, I just earned my Overcoming Claustrophobia Patch!
Buford: Ugh! Daylight! Ha ha!
Baljeet: Now what?
Phineas: Now we burrow back in and untie ourselves.
Buford: You gotta be kiddin' me! Who looked at this idea and said, "Yeah, that'd be fun"?! Y'see?! This is what happens when we have no intro!
Baljeet: I have been making mental notes of the paths and probabilities as I have gone along. It will be a piece of cake.
(Ferb gives a thumbs up.)
Isabella: If I just walk backwards, it should work.
Buford: To heck with this game! I'm just gonna chill here for a while. (gets pulled into the knot) Hey!!! Who's pullin' on my rope?!

(Cut to Perry walking into a restaurant called Jerry's All You Can Eat. He kicks open the door.)
Doofenshmirtz: Over here, Perry the Platypus. (Cut to Doofenshmirtz at a table with a Dagwood sandwich on it and a high chair sitting next to him.) I'm just having a little lunch. Why don't you pull up a chair and join me? (He sits in the chair and, of course, gets trapped.) Whadaya think? Pretty clever, right? It's my new high chair trap! I thought of a high chair cuz you're just a little guy. Arencha? Yes you are you're just a lil' guy. (Perry chatters angrily.) Hey, you're not getting outta this so why don't you enjoy the food. (Doofenshmritz force feeds Perry part of the sandwich.) It's All-You-Can-Eat, you know. (stops) Uh, ih, you're good? (Perry nods.) You're already full, right? Me, too. I barely touched my plate. That's how these all-you-can-eat places make their money. They charge you like you're gonna eat a week's worth, but then, when you fill up after, like, two plates, they-they've really made a profit. That's why I'm opening up my own All-You-Can-Eat Drusselsteinian buffet! (Shows him a video on a smartphone) Look. I've already made a commercial for it.

(Song: "Kronk for Hire" (instrumental))
(Cut to the ad)
Doofenshmirtz: All You Can Eat Drusselsteinian Buffet! It's food the way your mother never made! We've got Hassenfloffer Entrail Waterzooi, with Gopher Gut Au Gratin! Fuzzy Fungus Flugelbrotchen! And an assortment of tripe-based desserts! And those brave enough can try our new Mystery Lump! Remember, "Doof" spelled backwards is "fooD"!

(Cut back to Doofenshmirtz at the buffet.)
Doofenshmirtz: Y'know, come to think of it, it really should be called "the All You Can Stand", because Drusselsteinian food is terrible! That's the beauty of it. Nobody will be able to finish even one plate's worth! My profit margin will be HUGE! But, first, I've got to eliminate the competition, with this, (Takes out an inator) the Eat-It-All-Inator! You see, it gives people a huge appetite and everyone will eat so much that all of these All You Can Eat places will go out of busineeessssss! Then my restaurant will be packed! (Maniacal laughter) Maniacal laughter!

(Cut to Candace's bedroom where she and Stacy are pondering over the safe)
Candace: Whadaya suppose it is?
Stacy: It's probably some dumb boy stuff like firecrackers or turtle shells.
Candace: Or maybe it's his secret inner thoughts written as a sonnet. No, no, no, no, that's not it! I gotta think more like my brothers. Y'know, use my imagination.
Stacy: This could be dangerous.
Candace: Maybe it's a secret spy plan. Or a glass eye! Or Abraham Lincoln's beard!

(Cut back to Doofenshmirtz and Perry.)
Doofenshmirtz: Now, just watch what happens when I zap those people over there. (Perry jumps in his high chair causing Doofenshmirtz to fire off his inator. The ray bounces off a sneeze guard, off a lamp and hits Doofenshmirtz.) Huh? What happened? How could I miss? Oh, I'm so hungry all of a sudden! (He munches his way through the Dagwood sandwich on his plate finishing it whole.) Oh, that was great! I...I can cut out the middleman and do all the eating myself! (gets up) I'm going down for seconds. (He digs into the entire buffet. The man who was about to get his helping opens up a bag of chips. Cut to Doofenshmirtz eating other people's plates.)
Man: How can you eat like that and stay so thin?
Doofenshmirtz: Oh, I built an All-You-Can-Eat-inator that speeds up your metabolism so you don't gain any weight no matter how much you eat ever.
Man: You should mass produce that machine! Everyone would buy one! Well, you'd be a millionaire!
Doofenshmirtz: Pfft, don't worry about me making money, mister! I've-I've got a complicated plan. I—Like I'm gonna take advice from some guy in a diner.
(Perry bounces in his high chair out of the diner.)

(Cut back to the backyard.)
(Song: "Gordian Knot")

Phineas: There's a legend I've heard, or so it's been taught,
Baljeet: 'Bout Alexander the Great
Buford: And the Gordian Knot.
Phineas: Looked it up on the 'Net so that we could recreate it,
Now the knot we have here is quite complicated.

Isabella: It's got closed bends, loop splices, bowlines and lashings.
Phineas: Maybe we can loosen it with just a little thrashing.
Kids: Square knots, sheepshanks and all kinds of hitches.
Phineas: When it comes to constraint, there's an embarrassment of riches.

Kids: It's already a knot, so ready or not
We're gonna try to untie it, though it's terribly taut;
So it won't be for naught, we'll give it all that we've got
To untie the un-untieable knot.

Candace: We don't know what it is, but we know what it's not:
It's not a Gutenberg press or a coffee pot.
It's not a car or a tractor 'cause the safe's too small
And a fish or a piano wouldn't make sense at all.

Kids: It's already a knot, so ready or not
We're gonna try to untie it, though it's terribly taut;
So it won't be for naught, we'll give it all that we've got To untie the un-untieable knot.

To untie the un-untieable knot.

To untie the un-untieable...

Candace: Not...even close! (leaves) That's it, I'm gettin' the boys.

(Cut to an alleyway where we follow the bouncing platypus. Balthazar approaches him on his pogo stick. They bounce and look at each other. They then bounce away.)
Doo bee doo bee doo bah
Doo bee doo bee doo bah
Doo bee doo bee doo bah

(Cut back to the backyard. The gang is outside of the knot.)
Phineas: Looks like we all just got a few more moves to get untied. Except for Buford, who's managed to tie himself into a knot.
Buford: I'm a victim o' circumstance.
Phineas: Sure. We'd love to. As soon as we finish untying the Gordian Knot.
Candace: Alright, it's big and weird. MA!!!
(Cut to Linda in the kitchen getting a pie out of the oven.)
Linda: In a minute, Candace!

(Cut to outside Moe's All You Can Eat. Perry bounces his way in.)
Doo bee doo bee doo bah doo
(Cut to inside. Doofenshmirtz is stuffing his face.)
Doofenshmirtz: Ha! You're too late, Perry the Platypus! Buffet number two is history! I am starting to feel a little full though. Hmm, I thought it would last more than a few minutes. Better give myself a little boost. (Zaps himself) That's more like it! Wow, I am so hungry, I could eat everything at Buffet Number Three, baby! Yeah! (Perry bounces) Oh, give up, Perry the Platypus, those chairs are— (Perry throws himself and the chair at Doofenshmirtz. He falls over backwards as the chair smashes into pieces. The inator falls down and disappears.) Huh? Oh, man, I swallowed my inator. Oh, well, at least you can't destroy it now, because it's inside my stomach. So, today, I win! (Perry punches Doofenshmirtz's stomach and the inator zaps from inside his mouth. Doofenshmirtz feels his stomach.) Okay, you broke it. I can feel all the little pieces just rumbling around in there.

(Cut back to the backyard. The inator zaps Candace.)
Candace: I'm starving! What's that sweet smell?
Phineas: Probably licorice. We used it to make the ropes as a failsafe in case Mom wasn't around.
Candace: Perfect! (She drops the safe and runs into the knot.)

(Song: "Let's Go Digital" (instrumental, sped up))
(Cut to inside the knot where Candace stuffs her face of all the licorice like there's no tomorrow.)
Phineas: Wow, I never knew Candace was such a licorice fan. (Candace still munches on the licorice. Ferb gets out an umbrella and opens it.) Hey, thanks.
Buford: I am so in love with her right now.
Baljeet: What?
Buford: Nothin'.
Ferb: That's a solution to the Gordian Knot even Alexander the Great couldn't come up with.
(Candace finishes swallowing all of the knot. Linda walks into the backyard.)
Linda: Alright, Candace, what am I looking at?
Candace: I ate it! It was the size of the house and I ate it!
Linda: You ate it?
Candace: I know, I don't believe it either!
Linda: (looking at the safe) Well, what is that?
Candace: It's a safe. I can't open it.
Buford: Gimme that thing! I got an opener that can open anything! (He hits himself on the head with the safe, which opens.) ¡Para usted, señorita!
Candace: (takes out what was in the safe) A pencil?! This is what I've been obsessed with all day, a pencil?!!
Jeremy: Oh, I remember that! In grade school, a pretty girl loaned me that pencil and I've kept it ever since.
Candace: A pretty girl? (angrily) Who was she?
Jeremy: Candace, that pretty girl was you. See, those are your teeth marks.
Linda: Okay, Candace. You can eat the rest of that pencil. Unless you'd like to join us all for some chocolate triple layer cake.
All but Candace: Yay!
Candace: Ugh! Ohhhhhhh...
Phineas: Oh, there you are, Perry!
Jeremy: Hey, my baby teeth just fell out!
Buford: (giving the safe) Why don't you put 'em in here?
Candace: Ew. I mean cute!

End Credits

Seen when broadcasted by itself. (Song: "Gordian Knot")'

Candace:  It's not a car or a tractor 'cause the safe's too small 
 And a fish or a piano wouldn't make sense at all. 

Kids:  It's already a knot, so ready or not 
 We're gonna try to untie it, though it's terribly taut; 
 So it won't be for naught, we'll give it all that we've got 
 To untie the un-untieable knot. 

 To untie the un-untieable knot. 

 To untie the un-untieable... 

Candace: Not...even close!