Penny let out a happy sigh as she sat in between her older brothers, Phineas and Ferb, and their pet platypus, Perry, under a tree for a few long, peaceful moments. After those moments, Phineas finally broke the silence.

"So, Ferb, Penny, what do you wanna do today?"

Ferb shrugged.

"I honestly have no clue." Penny sighed, sitting up and pulling her legs to her chest.

"What about Perry?" Phineas asked. "What does he want to do?"

The three kids glanced at Perry, who chattered in response.

Phineas sighed. "Well, he's a platypus. They don't do much. I, for one, am starting to get bored, and boredom is something up with which I will not put! The first thing they're gonna ask us when we get back to school is "what did we do over the summer?". I mean, no school for three months. Our life should be a rollercoaster! And I mean a good rollercoaster. Not like that one we rode at the state fair..."

"Yeah, that was a bore." Penny sighed. She clearly remembered how she was clinging to Phineas out of fear as the roller coaster rolled up the tracks, then they all let out a scream as they zoomed down the hill, and ended just as soon as it reached the bottom.

The fair worker had ushered them out in a bored voice. "Please exit to the left."

"Man, that was lame." Phineas sighed.

"The guy sounded bored too," Penny said in agreement.

"Yeah." Phineas nodded at her. "Why, if I built a rollercoaster, I would..." His bored expression turned into an excited grin. "That's it! I know what we're gonna do today!"

The back gate opened, and the kids turned to see their mom, Linda, with a purse swung around her shoulder. "Phineas, Ferb. I'm gonna pick up a few things. You boys stay out of trouble, okay?"

"Okay, momma!" Penny smiled happily at their mom, running up to give her a huge hug. Linda smiled and hugged her daughter back and glanced at the boys. "Look after your sister today, okay? I'll be back this afternoon."

Phineas grinned. "Okay, Mom!"

When she walked out, Phineas broke into a grin. "We're gonna build a ROLLERCOASTER!"

Just as Linda was about to hop into her car, Candace ran over with hope on her face. "I'm in charge, right? You did tell them I'm in charge?"

Linda sighed as she got into her car. " Relax, Candace, nobody has to be in charge."

"But what if there's an emergency?"

"Like what?"

"What if a... What if a satellite falls out of orbit and crashes into the house?"

Linda sighed. "If that happens, you're in charge."

She drove off, and Candace pumped her fists in excitement. "YES!" She hurried to the backyard and opened the fence to find her siblings deep in work. "Mom says I'm in charge, conditionally."

"That's great, Candace!" Penny grinned at her.

Phineas, not looking up from his work or listening, mumbled, "Whatever."

Candace narrowed her eyes suspiciously at their workspace. "Wait a minute, what are you doing?"

"Homework." Phineas responded.

Candace raised her eyes. "It's summer."

"That's cool, you wait till the last minute then."

"Phineas!" Penny scolded her older brother.

Candace glared at them. "Well, I'm watching you. CONDITIONALLY!"

She walked into her house and picked up the phone. " Hello? Oh, hi, Stacy! No, I can't get to the mall right now. Mom just went to the store, she left me in charge, well, you know, conditionally."

She spent so much time talking that she didn't notice Phineas, Penny, and Ferb walking by the backwindow wheelbarrowing some supplies for their project.

"And if you go, can you see if Jeremy is there? No, no, he's the cute one that works at Mr. Slushy Burger. Yeah, and they never get into trouble, 'cause Mom never catches them. One of these days though, I'm going to see that she catches them red handed."

The sound of construction noises were heard and Candace growled in frusteration, yelling at her siblings through the window. "Will you hold it down, I am trying to use the phone!"

She turned back to her conversation with Stacy. "Mom left me in charge, so there will be no shenanigans today. What are they doing right now? Why do you ask?"

Candace's eyes raised in confusion and her mouth dropped. "What do you mean you can see it from your house? See what?!"

She ran outside and her mouth dropped open at the sight of a what looked like the begining of a rollercoaster. She narrowed her eyes at her siblings. "Phineas, what is this?!"

Phineas grinned down at her. "Do you like it?"

"Ooh, I'm gonna tell Mom, and when she sees what you're doing, you are going down!" She ran off, her yelling still visible to their ears. "Down! Down! Down! D-O-W-N, down!"

Phineas glanced at his siblings. " We're gonna need a blowtorch and some more peanut butter."

"More orange juice for me, please." Penny said, holding out her cup.

Candace hopped on her bike and rode right past Isabella, who smiled at her. "Hey Candace, is Phineas... home?" She shrugged when Candace didn't look at her and sashayed to the back yard, smiling sweetly at Phineas. "Hey, Phineas."

"Hey, Isabella."

"What'cha doin'?"

"Building a roller coaster."

"In your backyard?"

"Some of it."

"Wow!" Isabella grinned. " Isn't that kind of impossible?"

"Some might say!" Penny grinned down at the older girl. "But with my brothers, building this should be a sinch!"

"That's right, Pen!" Phineas grinned. "Pass me that wrench, will ya?"

"Here!" Penny tossed her older brother the wrench, who caught it perfectly. "Thanks!"

Isabella grinned up at Ferb. "Hey, Ferb."

He glanced at her and waved.

"Does your stepbrother ever talk?" She asked.

"He's not the talkative type." Penny said, hopping down to the girl. "Right, Phineas?"

"Yup!" Phineas grinned. "He's a man of action!"

Ferb banged his hammer on the nail, and the hammer accidentally bonked him on the nose. He blinked for a few times, causing Penny to giggle.

Isabella smiled. "I was gonna go to the pool, you wanna go swimming?"

"Sorry, Iz, but I think Phineas, Ferb, and I are in the middle of something." Penny smiled at the girl. "Maybe sometime?"

"Sure!" Isabella smiled. She waved at them after giving Penny a hug. " Okay, I'll see you later then." She waved at them again and walked off.

Penny waved back and glanced around, frowning. "Hey, where's Perry?"

Perry walked normally to a corner of the house, unlocking the secret lair entrance and zoomed down into his chair, where Major Monogram was waiting for him. When he plopped into his seat, his boss nodded at him. "Good morning, Agent P. The evil Dr. Doofenshmirtz is up to his old tricks. For reasons unknown to us, he bought up 80% of the country's tin foil. I want you to get over to his hideout right away. Find out what he's up to and put a stop to it. As always Agent P, it is important that your cover identity as a mindless domestic pet remains intact. Now, get out there. We're all counting on you."

The platypus saluted and hopped into his mobile and zoomed outside, quickly covering himself the best he could with his fedora as he past his owners, Phineas, Ferb, and Penny. They had been instructing exciting plans for the ride.

"So, the way I see it, the fuel rockets kick in at the mall's parking lot, then we release the snakes during the corkscrew at the interstate. I'm gonna go get the snakes."

Phineas walked down, followed close by Penny. Ferb pulled down his safety mask and turned on the blowtorch.

Candace ran excitedly into the store and up to her mother. "Mom! You gotta come home, right now."

Linda, not looking from the shelves, sighed. "Did a satellite crash into the house?"

" No, no, no. You gotta see what Phineas, Penny, and Ferb are doing!"

"Seems like we've had this conversation before."

"What do you mean?"

"I seem to recall you telling me that the boys were training monkeys to juggle bicycles, and when I come home, there was a stunning lack of monkeys."

" I still don't know how they cleaned that up so fast." Candace shook her head.

Linda moved the cart to a different shelf. "So, what's the emergency this time?"

"They're building a roller coaster!"

Linda raised her eyes at her daughter. "Candace, seriously, isn't Phineas a little young to be a roller coaster engineer?"

Penny waited patiently as her older brother talked to one of the workers in a car factory. He glanced down at Phineas. "Aren't you a little young to be a roller coaster engineer?"

Penny grinned and hopped onto Phineas's back. "Yes, yes he is!"

The man nodded, inspecting the paperwork he held. " Well, I must say, I'm very impressed, the forms all seems to be in order, although I'd never seen them filled out in crayon before. So, if there's anything I can get you, anything at all, just let me know."

"Do you think we could borrow one of those gadgets?" Phineas pointed to a robot arm that was fixing a car. Soon, after setting the machine up, the kids just relaxed as the machine did the work for them.

"This is the best." Phineas sighed happily.

Perry, now Agent P, swung into Doofenshmirtz' Evil Incorporated. Doofenshmirtz turned to the platypus with a grin. " Ah, Perry the Platypus, what an unexpected surprise. And by unexpected, I mean: COMPLETELY EXPECTED!"

The scientist pressed a button, and arms sprung out, trapping Agent P in place. The platypus glared at the scientist as he spoke. " I, Dr. Heinz Doofenshmirtz, have covered the entire eastern seaboard in tin foil, and when I put my giant magnet, next to my genius, Magnetism Magnifier, I will pull the East, in westerly direction, thereby reversing the rotation of the earth. You may ask yourself, why would he do this? What could he possibly have to gain? Well, let me just answer that question, I haven't really worked on all the bugs yet. I mean, tin foil alone costs a lot."

Agent P just rolled his eyes.

Back at the store, Candace still tried to tell her mom what was going on. "But, Mom, I'd tell you, they're building it, and it's huge!"

Her eyes caught on a poster on the wall, and she ran over to it, reading the cover. "Phineas, Penny, and Ferb present the Coolest Coaster Ever, now open"?" She grinned and ran off. "MOM!"

A second later, a group of kids ran up to the poster. "Phineas and Ferb got a roller coaster? You think we get a discount if we bring the flier?" A kid named Pedro asked.

His companion nodded. "Maybe we better take it."

They grabbed it just before Candace pulled her mom up to it. "There, look, look, look, see? I told you I'm not crazy, I told you!"

Linda stared at the empty wall in boredom. " And you're not crazy because...?"

Candace glanced at the empty space and let out a frustrated scream.

Linda sighed. "I see your point, Candace. No crazy person would scream at a post like that. I'll be at the dairy section if you wanna come yell at some cheese, or anything."

She walked off, leaving Candace flabbergasted.

After a few hours of work, it was finally time to open the rollercoaster to the public. Ferb readied the microphone and walked up to his sister, letting Phineas say the welcoming words. Phineas grinned as he took the microphone in his hand. "Ladies and gentlemen, boys and girls, children of all ages! May I present to you a spectacle most of the morning in the making: The Coolest...Coaster...EVER!"

With Penny's help, Ferb rolled up the curtain to reveal the roller coaster. Penny winced...she didn't remember it being that ridiculously high. She felt even more sick when a bird smacked into it and fell to the ground, dead.

Phineas grinned at the audience. " So, who wants to go first?"

Everyone raised their hands.

Penny anxiously sat close next to Ferb as the roller coaster slowly made its way up the too-close-for-comfort steep hill. Phineas sat carefully on the edge, explaining the rules to the kids, especially how to unbuckle a seat belt. " To fasten, insert the tab into the metal buckle. To release, just pull back on the—oops." He cringed as he dropped it.

Penny glanced at her older brother, her face pale.

Phineas hopped into his seat next to Penny. "Well, you get the picture."

The rollercoaster reached the top, and Phineas glanced at everyone. "You all signed the waivers, right?"

Penny let out a frightened gasp and buried her face in Ferb's shirt, who patted her back comfortingly as the coaster zoomed along the track, all around town. The kids screamed even more as snakes fell on them.

"GET IT OFF ME!" Penny screamed frantically. "GET IT OFF!"

Phineas moaned a little and pulled the snake off his frightened sister. "Relax, they're just rubber!"

They landed in a huge bucket of mud and rolled out again. Phineas glanced ahead and grinned. "Hey, look, there comes the AH-AH-AH-AH!"

The roller coaster looped around A shaped tracks while the kids screamed "AH AH AH AH!"

" ...I really make of my money back, I-I-I want a really spacey real estate, and sell it again." Doofenshmirtz was saying.

Perry glanced down at a nail on the ground, and using his tail he flipped it at the doctor, who surprisingly ducked. He smirked at Agent P. "Hah! You missed!"

The screw flew up to the roof and hit a line, and the force sent it sailing back to the doctor, nailing itself through Doofenshmirtz' foot. He screamed out in pain. He jumped around and accidentally released Perry, who knocked into him. During the fight, the doctor managed to turn on the Magnetism Magnifier.

Doofenshmirtz smirked at Perry. "Now you are too late! Quake in your boots and watch helplessly, as the unimaginable electromagnetic forces, pull the eastern seaboard, thereby reversing the rotation of the Ea-"

The tin foil flew off the buildings.

Doofenshmirtz frowned. "Well... that didn't work."

He and Perry watched as the tin foil formed into a huge ball, and the doctor panicked. "And now, we have a two-ton ball of tin foil traveling 200 miles per hour directly at us! Quickly, we must separate the magnet from the Magnifier before it's too late!"

The two began pushing the Magnifier.

"Now I know I have that club card in here somewhere." Linda mumbled as she dug through her purse at the cashier. "I always have it with me, but my purse is a disaster area, you know how it is."

Hearing screaming, Candace ran outside to see the roller-coaster zooming past. She grinned. That looked so bustable! She darted back into the store, yelling, "Oh, oh, oh, oh, oh! Mom? Mom!?"

" It's no use! It's no use!" Doof screamed as he and Perry continued pushing the Magnifier. "We are doomed!"

Agent P glanced up at a passing helicopter and grabbed his grappling hook, wrapping some of the rope around the Magnifier and shooting the rest at the helicopter. The helicopter flew up, taking Perry and the magnifier with it.

Doofenshmirtz grinned at the success. "You did it! You saved us, Perry the Platypus!"

He let out a yell as he tin foil ball rolled into him. "CURSE YOU PERRY THE PLATYPUS!"

The magnetism was so strong that it picked up the rollercoaster, lifting it high into the air.

Candace pulled her mother to the parking lot just as soon as the coaster was lifted into the air. "Look, look, look, see?"

Linda frowned at the empty space. "Okay, I give up, what am I supposed to be looking at?"

Candace glanced at it and her mouth dropped open. "No! It's not POSSIBLE!"

Linda nodded and walked off. "I'm gonna go get the cart."

"IT WAS RIGHT HERE AND IT WAS HUGE!" Candace glanced at the rollercoaster flying past and narrowed her eyes. "MOM!"

Linda walked past her. "Time to go. I have frozens."

Candace hurried after her mom. "Okay, so you think that Phineas and Ferb are still under that stupid tree in the backyard, right?"

"Well, yes, that would be my guess."

Candace grinned and took the cart from her mother, hurrying to the car. " Fine, then let's go home, now!"

Noticing the helicopter smoking, Agent P glanced up and quickly cut the rope, landing into the rollercoaster and right on Penny's lap.

Penny jumped at the sudden touch and glanced down at him, immediately engulfing him in a hug. "Sorry, Perry, freaked out right now."

He chattered in agreement.

Phineas glanced at his sister and hummed. "Nice hat, sis."

Curiously, Penny glanced at her head and pulled out a tiny fedora. She let out a scream and clung to Phineas and Perry tightly as the rollercoaster was suddenly launched into the air over a construction area.

Phineas narrowed his eyes in confusion. "Funny. I don't remember this in the blueprints."

They let out another scream as the roller car wrapped around an airplane tail. "And I'm pretty sure this is new." Phineas added.

Penny opened her eyes a bit and watched as the car knocked into the Statue of Liberty, accidentally bending it a little. The statue then launched up again, flinging them into a forest, where Penny met eyes with Jeremy, a Slushy Dog boy, standing behind the stall. He grinned at them. "Welcome to Mr. Slushy Burger, may I take your order?"

Phineas glanced at the kids. " Anyone want fries?"

The tree flung up and bought them (ridiculously) to Paris, landing right on the Eiffel Tower. It lowered them to another food cart. A seller looked at them. "Croissant?"

Phineas glanced back at them. "Anyone want a "quasson"?"

"No..." Penny squeaked. She let out another yelp as the car was flung into outer space. The kids watched as a satellite passed by.

Phineas glanced at his siblings. "You know, if that thing crashes into earth, Candace is in charge."

"Conditionally." Penny squeaked. She let out another yell as the car zoomed down towards home, the head of the car burning up like an asteroid.

Phineas sighed. "We should have charged more."

Linda pulled up the car to the house. " Okay, we're here, are you happy now, Candace?"

Candace chuckled maniacally and hurried to the back of the house, and grinned widely at the sight of an empty tree. She grinned and hurried back to her mom. " See, Mom? I told you they weren't there!"

Candace pulled her mom to the door, and Linda smiled. "Oh, hi, kids."

"Hi, Momma!" Penny waved with a grin.

"Hi, Mom!" Phineas called.

Candace just stared at them in shock. Linda patted her daughter's shoulder. " Come on Candace, help me with the groceries." She pulled Candace off, ignoring her "But, but, but, but, but, but, but..."s.

Once they left, more kids fell from the tree, huge grins plastered on their faces. "Hey Phineas, that was great."

" That was awesome! Can we do it again?"

" Sorry, only one ride per customer." Phineas responded with a shake of his head.

Isabella smiled at Phineas. "That was great, Phineas. So, what are you gonna do tomorrow?"

"No idea. Do you know, Phineas?" Penny asked.

Phineas shrugged. "Don't know yet."

Isabella kneeled down next to Perry, who suddenly joined them. "Maybe you could teach Perry some tricks."

"I think that would be great!" Penny grinned.

Phineas hummed, giving Perry a thoughtful glance. "Well, he is a platypus, they don't do much."

Ferb nodded. "They're the only mammals to lay eggs."

Silence.

Phineas grinned. " ...Maybe he'll lay an egg."

Isabella grinned and stood up. " Cool. See you tomorrow." She was about to walk out the gate when she turned and smiled at the siblings. " It really was the coolest coaster ever. You guys make a great team."

Phineas smiled. " Well, a family is a family, but I couldn't have asked for better siblings than Ferb and Penny." Phineas smiled as he patted Ferb's shoulder and wrapped an arm around Penny. "You know what I mean?"

Ferb suddenly burped, and Penny let out disgusted gasps, and her gasps soon turned into giggles. "Ferb, dude, that's gross!"

Phineas laughed, waving away the air. "Oh-ho-ho, man! I could smell the peanut butter!"

Isabella chuckled. "Well, that was impressive. See you, guys." She walked off, leaving the three under the tree. Penny happily grabbed Perry in her arms and hugged him tight.

Phineas smiled at his siblings. "So, what should we do tomorrow? There's a world of possibilities."

"We should make a list of what we should do during the summer!" Penny grinned.

The rollercoaster exploded, and a car alarm was heard, and a dog barked in the distance.

"MOM!" Candace called inside the house.

"GIVE IT A REST, CANDACE!"