(At the Fletcher residence in England at night)
Grandpa Reg: So kids, are you enjoying your visit to England?
Phineas: Oh, yes Grandpa. We even learned how to use real thatch.
Grandpa Reg: Well, thatch terrific! (he laughs with Phineas) That was a good one.
(Candace and Stacy groan)
Stacy: There's nothing to do.
Candace: Nothing for us to do.
Grandma Winifred: What? Why don't you read my old collection of Sherlock Holmes? I've got the whole collection right here.
Stacy: Gee. Thanks, Mrs. Fletcher.
Grandma Winifred: Dinner's at 1900. That's 7 o'clock for you Yanks.
Candace: Ah, yes. Reading. That's what they did before they invented fun.
Grandma Winifred: I heard that.
Candace: Well, it's better than nothing. (Both she and Stacy begin reading) Hmm? Mmm-hmm... Hmm...

(Sunrise of the next morning)
Lawrence: Okay, is everybody ready? We're going to take you kids to see the London Eye.
Phineas: What's that?
Lawrence: One of our largest Ferris wheels in the entire universe.
Phineas: Cool!
Lawrence: Girls, are you ready?
Candace: Wait, wait, almost finished.
Lawrence: Candace, you stayed up all night just to finish that book?
Candace: No, no. We finished the whole collection.
Grandma Winifred: Before they invented fun, indeed.
Phineas: Hey, where's Perry? Oh, there he is.
Grandpa Reg: See you later, old boy. Be good now.

(Perry opens the grandfather clock and steps in, falling into a lair, where he enjoys a cup of tea)
Doo be doo be doo ba, doo be doo be doo ba
Doo be doo be doo ba,
Major Monogram: Good morning, Agent P. Doofenshmirtz is up to no good here, in the UK. And, uh, after your last mission in London, we ran into some trouble with the British Spy Union. So joining you today is Agent Double 0-0. And joining me today is the lovely Inspector Initials.
(Agent Double 0-0 drops down from the ceiling and lands in the chair, whilst Inspector Initial splits the screen with Monogram)
Inspector Initials: Double 0-0, you and Agent P will be assigned the same mission against Dr. Doofenshmirtz.
Agent Double 0-0: You realize this man is a Platypus?
Inspector Initials: They're American, Double 0-0. Just be glad it's a mammal.
Major Monogram: Ooh. Rrreow. Well, go get him, Agent P.
Agent Double 0-0: What? That's it? No files? No location? No contact? What kind of a mission is this?
Major Monogram: It was enough for the mammal.
Inspector Initials: Ooh. Rrreow.

Grandpa Reg: Alright, you lot. Have a splendid day in London. We'll be back tonight after the International Haggis Festival.
Lawrence: There's twenty-nine individual flavors!
Grandpa Reg: Cheerio.
Linda: Here are your tickets for the London Eye. You might want to get in line now, 'cause it looks pretty crowded.
(Carnival music)
Linda: We'll pick you up around 4:15. Bye, kids.
Grandma Winifred: Have fun!
All but Ferb: Bye!
Phineas: Candace, you know what? Ferb and I will meet you back here later. See ya!
Stacy: Bye, guys! (to Candace) Hey, let's go shopping!
Candace: Did you hear that? Even in England, my brothers have some scheme planned.
Stacy: How can you tell?
Candace: You don't have to be Sherlock Holmes to—Ooh! Stacy, that's it! Who did we stay up learning about? (she hakes her) Who is the total king of busting?
Stacy: Sherlock Holmes?
Candace: Yes! Maybe I can finally bust the boys once and for all if I use Holmes's method of deduction! Come on. This will be fun! You could be Dr. Watson.

(Perry and Double 0-0 sit in Perry's hover car, with Agent Double 0-0 being very cramped and setting it off balance)
Agent Double 0-0: That's it. We're taking my car.
(They drive down the streets of London in Double 0-0's car)
Agent Double 0-0: Now this is a motor car. It has pretty much everything. Radar, Subatomic Sonar, Nuclear Particle Response System, and a MP3 player. (Button beeps) Don't touch that, it's the ejector– (The seat ejects sending Double 0-0 flying out of the car, which eventually comes to a rest as Double 0-0 catches back up and retakes the driver's seat) And I suppose you think that's funny.
(Perry chatters and the car shoots off)

(Candace and Stacy walk down the street with Candace wearing a deerstalker hat and robe similar to Sherlock Holmes, and Stacy wearing a bowler hat like that of Dr. Watson)
Candace: By using Holmesian Deduction, we'll be one step ahead of the boys. We can get Mom and finally show her–
Stacy: Ooh. Shoes. (Stacy stops at a storefront)
Candace: Stacy? I need you to focus!
Stacy: Sorry, sorry. Got a little distracted there. You know, London, cool stores, shopping.
Candace: There they are! Now why are they going into an auto parts store? Alright, Watson. Here's where the deducing begins. (she gasps) They've acquired a fleet of automobiles. And they're in there buying a bunch of little air fresheners for them. Or... they're buying motor oil for their giant robot! What do you think, Stace? Stace?
Stacy: (returning with shopping bags) What?

(At the Big Ben, Perry and Agent Double 0-0 bust in and find Doofenshmirtz)
Doofenshmirtz: Perry the Platypus? Oh, who's your little friend here?
Agent Double 0-0: I'm Agent Double 0-0, from Her Majesty's secret service.
Doofenshmirtz: Double 0-0? I-isn't that just triple "O"?
Agent Double 0-0: No, that's not how you say it.
Doofenshmirtz: It spells "OOO", does it?
Agent Double 0-0: It's just Double 0-0.
Doofenshmirtz: He's "P" and you're "OO", so together you spell-
Agent Double 0-0: No, they're not "O"s, they're zeros. Alright?
Doofenshmirtz: I was just going to say "Oop". Looks like I struck a nerve there!
(He presses a remote and two traps spring out, holding perry around the waist, but Double 0-0 around the shins)
Agent Double 0-0: Hey!
Doofenshmirtz: I must apologize, all of my traps are platypus-sized.
Agent Double 0-0: What about this then? (he motions to a large rocket engine above them)
Doofenshmirtz: Oh, that. You see, as I get older, I find it's harder and harder to read my small, little wristwatch. So, I will launch Big Ben into space, and fly it all the way to the Tri-State Area. (He demonstrates on a scale model) La-la-la, here I am, la-la-la, I just woke up and want to know what time it is – Yes! I am a genius!
Agent Double 0-0: So that– That's your whole plan?
Doofenshmirtz: Well, in a nutshell, yes. What do you think?
Agent Double 0-0: Am I on one of those hidden camera shows? You realize you could just buy a bigger watch? Or maybe a wall clock?
Doofenshmirtz: Yes, but then I would have to drive to a store, and find a parking space, then you have to choose from, like - dozens of styles, I- It just seems like so much work. This will be much less complicated.

Candace: (upon entering the auto parts shop) Okay, Watson. Excuse me sir, were these boys in here earlier?
Worker: Well, them two bics were 'angin' about an' they got a bit o' the bushies an', uh, also ran back an' carted off some ol' bangers that ah didn' need. Oi! Aren' they a bit harrish for them kind o' bushies?
Candace: Stacy?
Stacy: (Flipping through a Cockney for tourists book) I'm working on it. Ah! He said "They were here, they carted away some junk from out back, and, aren't they a little young to be doing that?"
Candace: Yes. Yes they are. (Stacy and Candace enter the back lot) Aha! It's crawling with clues out here! Hmm... Look at these circular indentations in the dirt. (She sniffing) And the subtle scent of rubber in the air. By Jove, Stacy! What could it be?
Stacy: Uh, "Free Tires"? (She looks at a sign advertising "Free Tires")
Candace: Maybe, maybe... We need more clues!
(Stacy graons)

(Song: Elementary)
We've got a mystery to solve
Clues and puzzles to resolve
It's elementary
Separating fact and fiction, gonna get me a conviction
Oh, what is truths, and what is lies?
It's elementary
I see it with my private eyes, grab your magnifying glass
'Cause deductive reasoning's a gas
It's elementary (Elementary, it's elementary, yeah) (Elementary, it's elementary, yeah)
Oh, yeah, it's elementary (Elementary, it's elementary, yeah)
Yeah, it's elementary

Candace: Stacy, I think I'm close to figuring it out.

The rocket engines under Big Ben begin to start up)
Doofenshmirtz: I'm going up to the top of the tower, I'm sure you two have a hot time together! (He laughs and exits)
Agent Double 0-0: Don't worry, Agent P. I'll have us out of these before you know it. (He activates a laser on his watch and begins cutting through the restraints)

Candace: There they are. (Phineas and Ferb get into a taxi that promptly pulls off) They dropped a notebook. The page is torn, but it says "To big race 1600 Water S." Water Street! The final clue! They're having a race at 1600 Water Street! Ooh, I gotta call Mom! (To her mom through the phone) And that's why you've gotta come down to 1600 Water Street. (She and Stacy arrive at 1600 Water Street which is nothing but an old abandoned building) Huh? I don't get it! I thought I'd figured it out.
Linda: (On the phone) Hello? Hello? Candace, are you there?
Candace: Sorry, Mom. Disregard everything I said.
Linda: Okay, sweetheart.
Grandma Winifred: Remember, no snacking. Dinner's at 1900.
Candace: Oh, okay. See you later. (To Stacy) What if 1600 isn't a place, but a time?
Stacy: I didn't get that impression.
Candace: Impression! Stacy, you're a genius. Wasn't it in one of those Holmes stories that they used pencil lead to reveal an impression on paper? Well, if my hunch is right... (She takes an impression of the missing half of the page) "To do today: Big Ben race to Thames at 1600 for water slide fun"! Stacy, 1600 is 4 o'clock which is right now! Let's go!

Agent Double 0-0: (firing his laser) Just a few more minutes.
(Perry notices a remote, grabs a brick and throws it at the remote button, releasing them both)
Agent Double 0-0: Ow! Oh, there you go. Good thing I had the watch laser. Now Doofenshmirtz took the stairs, but if we work our way up the inner mechanism of the clock, he'll never see us coming.
(Agent Double 0-0 starts climbing up through the clock gears)
(Perry watchs briefly, then calls the elevator)

(Candace and Stacy arrive at Big Ben which has a giant water slide surrounding it)
Stacy: Wow! Candace, you're amazing! You totally figured it out!
(A kid wearing a tire rides the slide, bounces across the water and lands in a car on London Eye)
Candace: Yeah, I guess I did. Now, on to the busting.

Phineas: (Operating the water slide) Next!
(A grabber grabs a boy in a tire and takes him up the tower)
Candace: Phineas!
Phineas: Hey, guys! Do you like it?
Candace: I figured you guys were up to something. The tires, the pipes, I see what those were for, but what was with the pineapple?
Phineas: Oh, that was for Ferb. He was hungry.
Candace: (mocking) Oh, and the butter too, huh?
Phineas: No, no. He's using that for speed.
(Ferb, at the top of the slide, butters himself up. He rides down the slide, bounces off the River Thames and lands in a ferris wheel car at warp speed)
Referee: (Inside the car) It's a new world record!
Candace: Mom's gonna flip when she sees about this! (She starts dialing the phone, but the grabber takes her up the tower and she goes down the slide, screaming)
Linda: (answering the phone) Hello? (Candace tries to speak, but her speech is gibberish due to a bumpy area in the slide)
Someone with a thick cockney accent. (she turns off her phone) Wrong number.
(Candace continues to slide)
Stacy: Can I take a turn?
Phineas: Go for it. (Stacy goes up) Last customer of the day. (He goes up too)
(Candace slides off the slide and bounces into a car)
Stacy: Whoo-hoo! (slides off, lands in Candace's car)
Phineas: That's what I'm talking about! (slides off, lands in car)
Candace: Ooh! It's 4:15. Mom should be here. Mom! (bangs car glass) Look!Look up here!
Linda: (not hearing this) I hope the kids had fun today.

Doofenshmirtz: (On top of the tower) Well, It's about time!
(He presses a remote, the rocket engines fire, and Big Ben starts rumbling)

Candace: Mom, look! Mom, Mom!!!
Stacy: (seeing Big Ben about to launch, taps on Candace's shoulder) Uh...Candace?!
Candace: Not now, Stacy!
Stacy: But --
Candace: (she bangs on glass more) Mom! Mom!

(Big Ben launches)
Doofenshmirtz: (Doofenshmirtz laughs maniacally) Hey!
(Perry arrives at the top of the clock and kicks Doofenshmirtz and takes the remote)
Doofenshmirtz: (landing on the water slide Phineas and Ferb Built) Hey, look at this! It's like a ride! (part of the slide begin coming off) Woo-hoo! Cannonball! (The entire slide breaks into pieces and land in the water. Doofenshmirtz lands on the pavement) Well, I was expecting a bigger splash...
(Perry presses a remote, and Big Ben lands back in place)

Stacy: (Watching it all) Whoa!
Candace: Mom!
Linda: Here come the girls!
(Candace and Stacy's car lands, and Candace gets out)
Candace: Mom, you gotta– !
Linda: Oh, look at your cute outfit!
Candace: Mom, you gotta look at– (Candace motions towards Big Ben)
Linda: Oh, Big Ben! Gorgeous!
Candace: (deadpan) But-but-but-but-but...
Winifred: Ah, here come the boys.
(Phineas and Ferb's car comes down, they come out)
Phineas: Hey, Mom, you missed all the fun.
Linda: Looks like we did. All right, let's catch a cab and head home. Come on!
Phineas: Looks like Candace and Stacy did some shopping.
Ferb: I'll never understand fashion.

End Credits

(At Big Ben, Agent Double 0-0 grasps onto its pendulum trying to reach and access ladder. This continues for several seconds until he finally comes out of the clock face)
Agent Double 0-0: Ah-ha! Well, that took longer than I thou— Wait! (He looks at watch several times and sighs) Oh, I wish I had a bigger watch.