The guys decide to hold a competition between the girls to see which are better at sports. Also, the build a telescope in the backyard. Then, Jeremy's sister is tormenting Candace. Doofenshmirtz wants to be the winner of a dog show, and makes an attempt to liquefy a steak.

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.

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.

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.

Phineas and Ferb open Chez Platypus, which becomes the trendiest restaurant in town. Jeremy asks Candace out on a date to the restaurant. Meanwhile Doofenshmirtz goes on another date from his online dating service, and vows to destroy all love in the tri-state area if the date doesn't go well.

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.

Perry the Platypus is reassigned and forced to move to the Quad State area with a new family and battle a new villain, the Regurgitator. During his new assignment, Phineas, Ferb, and Candace put in every effort to find him, hoping he'll return to them.

To play a game of indoor hide-and-seek Phineas and Ferb shrink down their friends including, their new extreme fan, Irving. Meanwhile, Dr. Doofenshmirtz attaches a nanobot to Perry in an attempt to discover where he lives.

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 Candace finds a rabbit, she wants him as her pet, but in hindsight, he's actually a rouge agent trying to find Perry's secret lair for information. Meanwhile, Phineas and Ferb try to make x-ray glasses. And since Perry isn't around to stop his latest plot, Doofenshirtmz faces an unusual new foe.

Perry the Platypus is reassigned and forced to move to the Quad State area with a new family and battle a new villain, the Regurgitator. During his new assignment, Phineas, Ferb, and Candace put in every effort to find him, hoping he'll return to them.

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.

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.

Phineas and Ferb plan to put Danville on the map by building the world's tallest building. However, Candace teams up with Albert and utilizes his expertise to bust her brothers. Meanwhile, Dr. Doofenshmirtz wants to be responsible for all the evil in the Tri-State Area, and since he believes that evil levels rise during a full moon, he plans to rotate it so that only the infamous "dark side of the moon" faces Earth.

Phineas and Ferb's newest invention is a pair of boots that make the wearer extraordinarily fast. Candace decides to wear them so that she can be in two places at once; at Jeremy's family picnic, where she runs into Mrs. Johnson, and also at the library where she promised Mom she would read to the kids. Meanwhile, Dr. Doofenshmirtz's building is put up for sale so he tries to convince a prospective buyer, Annabelle, who turns out to be a long lost relative of the Johnson family, that it is not worth buying.

When Ferb's cousins visit from England and challenge him to a soccer match, he and Phineas warp the walls of physics and build a high tech 3D stadium. Meanwhile, convinced that her relationship with Jeremy depends on her being more proper, Candace enlists the help of Ferb's British cousin, Eliza, to teach her the rules of etiquette. Back at Doofenshmirtz Evil Inc., Dr. Doofenshmirtz is sick in couch but forces himself to set off his \"If-A-Tree-Fell-in-the-Forest-Inator\", which causes any tree that falls to say his name.

Potato gremlins appear all over town when Phineas and Ferb clone a potato chip from Buford and it mixes with his DNA; Doofenshmirtz tries to summon the Spartan army with his historical army retrieve-inator.

Phineas and Ferb create their own language, Ferb Latin, which quickly catches on. Unfortunately for Candace, she awakes from a massage puzzled to find everyone else speaking a language she doesn't understand. Meanwhile, Dr. Doofenshmirtz decides to use propaganda as his new "-inator," believing that it will work since people will believe anything they read.

Meap's world is put in danger and the boys try to help him save the universe when they travel to Seattle. Meanwhile, Doofenshmirtz visits former nemesis Peter the Panda.

When one of Dr. Doofenshmirtz's "-inators" zaps him and Agent P into the middle of nowhere, they must embark on a comical journey filled with twists and turns to return home.