Phineas and Ferb find a time machine at a museum and travel back to the Jurassic Age. Meanwhile, Perry is sad when Doofenshmirtz replaces him with a new nemesis, Peter the Panda, so he confides in a relationship talk-show host.

The boys and Candace hatch a plot to reunite their mom and dad's favorite band for a wedding anniversary concert.

The boys stage a chariot race through the town's streets after learning about ancient Greece. Meanwhile, Dr. Doofenshmritz creates a giant robot named Norm to destroy Perry, once and for all.

Perry wants to destroy footage from a traffic camera to keep his identity a secret, as Candace tries to use the film in hopes of proving her brothers create unusual stuff. Then, the guys decide to build the largest bowling ball and pins in the world, while Doofenshmirtz wants to rid the world of rainbows.

Phineas and Ferb create the world's largest golf course, and since Candace is sick, she asks her best friend Stacey to bust the boys for her.

The boys learn about one of Ferb's Victorian ancestors, who helped a scientist create a monster. Meanwhile, Doofenshmirtz recalls the story of his great-great-grandfather Dr. Jekyll Doofenshmirtz.

The boys create a cartoon and cast themselves as superheroes and Candace as the villain, while Perry attempts to defeat Doofenshmirtz, who has taken control of the power of dance.

The boys build a rocket ship to get a good look at a star named for them, and Candace accidentally takes a ride with them just as she is trying to find the courage to ask Jeremy to a dance, while Isabella tries her best to do the same with Phineas. Meanwhile, Perry must stop Dr. Doofenshmirtz, who, not only is conveniently in space too, but has created a massive spacestation in an attempt to get revenge on "Huge-Hands-Hans".

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.

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 becomes concerned that he is losing his mental edge, the boys invent a cerebral stimulatory hat, or "Brain booster," to help him. But when the hat exceeds expectations and makes Baljeet exponentially smarter, he suddenly views everyone else as beneath him and becomes a threat to civilization by taking Earth's atmosphere and bringing it to the moon. Meanwhile, Dr. Doofenshmirtz plans to use his "Key-Find-Inator" to collect all the keys in Danville in hopes that it will lead to the Key to the City.

The guys help their dad unearth a missing piece of Danville history; Doofenshmirtz tries to make himself younger to win a children's film festival.

Candace accidentally turns into a fluid when she comes into contact with a device that turns solids into liquids. Meanwhile, Doofenshmirtz turns himself into a platypus to defeat Perry in battle.

Agent P's fate is finally revealed in the action-packed finale of the two-part television special that left Phineas, Ferb and the gang hanging...literally off an unchartered gorge and Candace frantic over a phone call with Jeremy that left their relationship status in limbo. Now, with Agent P nowhere in sight, Dr. Doofenshmirtz and Major Monogram square off against evil Carl who controls a set of familiar-looking robots to take over the OWCA, in one of the biggest battles yet.

Phineas and the gang introduce Ferb and Perry to their newest project - training domesticated squirrels to live in the wild. Meanwhile, Dr. Doofenshmirtz aims to do a better job of seeing through his evil plans now that Agent P is back.

Agent P quickly figures out there is more to Norm's odd reality show that celebrates the eventful life of his creator Dr. Doofenshmirtz, which is recreated through flashbacks and special guests.

Isabella unintentionally admits her feelings for Phineas in a letter. Meanwhile, Doof invents an inator to help change his misfortune

After Doofenshmirtz is defeated, a new threat in the 2nd Dimension emerges, leaving it up to Phineas, Ferb, Candace and her resistance fighters to defeat this new foe.