Dad accidentally sells Candace's favorite doll at a yard sale. Phineas and Ferb become detectives and interview various people to find the doll. Meanwhile, Perry the Platypus tries to get the doll back from his nemesis.

Candace panics when she inadvertently agrees to babysit Jeremy's little sister Suzy but to her surprise, Suzy is docile in the absence of her brother, saying that when Jeremy isn't around, she's "off the clock." The two of them bond and Suzy shows Candace how to get Phineas and Ferb to bust themselves. Meanwhile, the boys build a replica of Niagara Falls in their backyard with the intention of riding over the falls in a barrel. Back at Doofenshmirtz Evil Inc., Dr. Doofenshmirtz decides to increase his carbon footprint, (though he doesn't know what that is), by inventing a Carbon Footprint-inator.

Phineas and Ferb build a robotic rodeo in the backyard. Candace tries to prove she can focus so she can go to a concert with Stacy. Doofenshmirtz stalls to finish his entry into the Inator Creator competition.

Khaka Peü Peü arrives in Danville to challenge Phineas and Ferb after the boys are mistaken as a superhero (while wearing an indestructible suit they designed to safely conquer their newly built extreme skate-track) known as The Beak. With the super villain wreaking havoc, it's up to Phineas and Ferb to thwart him while Dr. Doofenshmirtz tells the people of the Tri-State area that he is in charge, in hopes that they will actually just go along with it. Meanwhile, his brother Roger is worried that everyone will blame him for the recent super villain catastrophe so he decides to make Doofenshmirtz Mayor.

It's the summer solstice, so Phineas, Ferb, and their friends decide to travel around the world in one day in an effort to create the "biggest, longest, funnest summer day of all time". But not everyone believes they can actually achieve what they have set out to do, especially Buford. Candace tags along because Jeremy is on a trip to Paris, and she fears that there he may meet other girls. Also, Isabella finds her affections for Phineas sorely tested when his steadfast focus on achieving his goal puts pressure on her. Meanwhile, Dr. Doofenshmirtz takes a father trip to Tokyo, Japan with Vanessa, but sets out with Perry and Major Monogram to find her when she joins Phineas, Ferb and the others.

Phineas and Ferb head to the Tri-State area’s annual sci-fi/comic book convention to meet their hero, special effects guru Clive Addison. Their plan gets sidetracked when they’re swept into a duel between fantasy fans and sci-fi geeks. Meanwhile, Candace tries to keep secret that she’s a fan of Ducky Mo-Mo, another convention staple. Across the convention hall, Dr. Doofenshmirtz has taken television executive Jeff McGarland hostage so he can pitch him a show he’s developed, Doof ‘N’ Puss.

When Phineas and Ferb spin the house in order to paint it more quickly, Candace, inside the house, gets dizzy and collapses. She wakes up in the magical land of Odd and heads down the yellow sidewalk to Bustopolis to meet the Wizard.

A musical in which Phineas and Ferb revisit the day they built a gigantic roller coaster in their backyard. Doofenshmirtz tries to pull the East Coast to the west using tinfoil and a huge magnet.

When Baljeet saved his life, Buford vows to become his slave. Then, when Candace and Stacy accidentally send bad pictures of Candace to Jeremy's cell phone, they get a job at Mr. Slushy Dawg in order to get his phone and delete the pictures before he sees them.

Phineas and Ferb set out to build a bigger plane than Howard Hughes' wooden Spruce Goose, so they build it out of papier-mâché, to do a similar theme to the Spruce Goose, complete with in-flight service and entertainment. Dr. Doofenshmirtz is doing his part to be green by using recycled materials to build an "Evaporator-inator" to dry up all the pools in the Tri-State area. Meanwhile, Candace and Stacy attend Jeremy's pool party only to discover an adventurous Australian girl is capturing Jeremy's attention.

While in London, Candace and Stacy decide to take a page out of Sherlock Holmes'…entire collection, to figure out what Phineas and Ferb have planned for the London Eye. Meanwhile, Perry must team up with British agent 00 Zero in order to stop Dr. Doofenshmirtz from moving Big Ben to the Tri-State Area.

It's another average, logic defying day for Phineas and Ferb, until a crashed space pod, carrying an unbearably cute alien, Meap, thrusts the boys into another adventure in space! Everyone has a different role to play, while Candace holds on to Meap by accident, Ferb is fixing up the ship, as Phineas uses the new cute tracker to find where their new friend is, to the slight irritation of Isabella, as he can't get what *cough* is causing cute interference, but of course, it all has to lead up to the big explosive finale in SPACE -ace-ace. Meanwhile, Doofenshmirtz has a new plan, simplistic in nature, but buried in an avalanche of backstory, oh dears.

Phineas and Ferb learn that Baljeet has signed up for rock camp and worries he may get his first failing grade. So the boys help by forming a band to help him express his feelings, especially for math. Meanwhile, Candace wonders why Jeremy doesn't give her a cool nickname as Stacy gets close to Coltrane, the rock camp director. Doofenshmirtz's latest plan has him wanting his own army of babies by broadcasting his heartbeat all over the tristate area.

When an early end to their daily project causes Phineas and Ferb to mistake an egg for Perry's, the boys use all their technological knowhow to help hatch the new part of the family. However Candace has different plans for the egg, as a nature show brings her to be the one to convince Phineas and Ferb that the newborn will need a real mother. Meanwhile, Doofenshmirtz is doing all he can to convince Perry that his latest scheme really is evil.

Unsure of his own dancing skills when he agrees to go on a TV show with Candace, Phineas and Ferb develop a device to help Jeremy imitate the dance moves of a professional. Meanwhile, Dr. Doofenshmirtz and several other villains try to broadcast an evil message during the taping of the show.

Phineas and Ferb create an orb that allows its user to pass through objects to help find Linda's guitar pick, Dr. Doofenshmirtz tries to destroy a statue honoring his brother Roger.

While Phineas and Ferb get the bubble ready, Isabella and the Fireside Girls head out to the "Old Abandoned Old Abandoned Amusement Park" where the maracanut tree is and try to get the sap from it. Meanwhile, Isabella's pet dog, Pinky tries to stop his nemesis, Professor Poofenplotz, from stealing hairspray.

The boys reconstuct one of Doofenshmirtz's inventions to discover what it does after it lands in their front yard.

After taunting the boys for going to search for the "Lake Nose Monster", Candace begins freaking out on her lifeguard job, seeing the monster at every turn. Meanwhile, Dr. Doofenshmirtz tries to remove all the zinc from the lake, though even he's not sure why.

Phineas and Ferb have a new pet, Goldy the goldfish, and to help make Goldy feel less lonely, Phineas and Ferb have built an aquarium with many other creatures. Meanwhile, Perry must stop Doofenshmirtz from a food related childhood revenge story.

The family takes a short sail trip out to sea, but a storm causes them to wind up stranded on a remote island. To pass the time, Phineas, Ferb, and Isabella, build a set of treehouses with the most modern conveniences, to Candace's dismay, as she wants to get back home in time to attend Jeremy's party. Meanwhile, Perry the Platypus, who was left behind, must get away from the watchful eye of Baljeet and Buford, so he can go on his mission to stop Dr. Doofenshmirtz's latest plot.

After Ferb accidentally leaves his skateboard at his grandparents' house, he and Phineas develop a teleportation device that can retrieve any object. Meanwhile, Dr. Doofenshmirtz tries to rid the world of mimes.

Phineas and Ferb are decorating their city for the arrival of Santa Claus. But when the evil mad scientist Dr. Heinz Doofenshmirtz uses a machine to ruin the holiday, Phineas and Ferb must find a way to fix it and save Christmas.

Curious as to what Perry's chirping sound really means, Phineas and Ferb create a "Perry Translator". But they soon find it's not just bound to translating platypuses, platypi, platypeople? Meanwhile, Perry himself is caught in a plan involving a shark cage that is half off, a remote to open the dam, complicated acronyms and the high tech BO-AT.

Fed up with her brother's inventions always disappearing, Candace enlists the help of everyone in the neighbourhood to build and watch a big and obvious invention, that they might finally see exactly what happens to everything. Meanwhile, is it mime? No, it's Doofenshmirtz' new Invisibility Ray.