As the family goes to Mt. Rushmore to celebrate Candace's birthday, Phineas and Ferb build a rollercoaster and Candace wants to catch them in the act. Agent P attempts to thwart Dr. Doofenshmirtz's plan to drill a tunnel to China.
After turning their mom's car into a race car, Phineas and Ferb enter the Swamp Oil 500. Dr. Doof attempts to deflate everything by using his blimp./ Agent P tries to thwart Dr. Doof's plan to steal all lawn gnomes, while the boys build a huge beach in their backyard.
Dr. Doof plots to control termites to make them eat all the wood, so that people would buy aluminum siding from him. Phineas and Ferb use an invention to create a winter and summer playground paradise, while Dr. Doof sets out to melt all the chocolate in the area with his machine.
After watching a mummy movie, the boys set out to have their own mummy. Candace wants to try out for The Next Super American Pop Teen Idol Star. Agent P tries to thwart Dr. Doof's plot to take over the Tri-State Area with a giant robot.
Dr. Doof invents a machine that hypnotizes people in order to make them attend his birthday and follow his orders. The boys make Candace star in a film adaption of her beloved play, but they turn it into a monster movie.
As the boys and Candace head to their grandparents' cabin by the lake, they run into trouble that involves coming across Bigfoot. The boys surprise Candace by remodeling her old treehouse. As Dr. Doof plots to get revenge on his brother Roger, Perry attempts to stop him.
As the boys come across a broken time machine from the museum, they attempt to fix it and end up going back in time as they drag Candace along. Perry is upset when Dr. Doo replaces him with a new nemesis called Peter the Panda.
After they are unable to go to the circus, the boys decide to make their own circus in the neighborhood. After Candace works in a toy store, she challenges the boys to create their own toy; they end up making a Perry action figure.
As Isabella can't seem to be get rid of her hiccups, the boys set out to build a haunted mansion to scare them out of her. As Dr. Doof attempts to destroy his old mentor's hideout, Perry tries to stop him. Candace clashes with Jeremy's annoying sister, Suzy.
As the family travels to England to visit Lawrence's parents, the boys decide to hold a medieval tournament, while Candace takes part in the festivities to get Charles to like her. As the boys have grand ideas to achieve but there is only two of them, they decide to build robot versions of themselves.
As Candace tries to throw the best birthday party for Linda, the boys get in the way and beat her to it. Dr. Doof tries to shrink everything that he doesn't like. When Isabella's dog eats her sash, the boys attempt to retrieve it by building a mini-submarine.
As the boys join a fashion line, it gets in the way of Candace's dream of becoming a supermodel. In order to avoid waiting in line, Dr. Doof makes clones of himself. The boys make the biggest sundae machine for Isabella. Vanessa tries to convince her mother that her dad, Doofenshmirtz, is evil.
The boys build a monster truck track in the backyard in order to teach Candace how to parallel park. Dr. Doof wants to get rid of the competition as he shows his new line of monster trucks to investors. The boys and their friends go on a treasure hunt.
In order to help Lawrence celebrate his wedding anniversary with Linda, the boys set out to reunite their parents' favorite band for a concert. Dr. Doof wants to throw a Sweet 16 birthday party for Vanessa.
As Candace and Stacy travel with their favorite band, their excitement soon fades away when they find out that they're such snobs. The boys attempt to give their grandfather a chance to relive his wild days as a daredevil.
As Candace finally manages to catch the boys in the act when they are building a flying car, they are sent to military school where they have to adapt to a harsh environment.
The boys bring back to life an ancient Greek chariot race, while Dr. Doof creates a robotic man named, Norm. As Candace grows tired of not being able to bust her brothers, she turns to a reality show that specializes in catching little brothers in the act.
As the boys help Grandma Betty Jo to set up a roller derby rink to have a rematch with Hildegard, Candace ends up competing against Jeremy. As the boys decide to take the day off, Candace wonders what to do since her only mission was to bust her brothers.
As the boys help bring a caveman back to life, he ends up crashing a costume party that Candace is attending. Dr. Doof wants to get rid of all people dressed as sandwiches. The boys help Buford find his missing goldfish.
When the boys invent a teleportation device, they end up causing Candace and Perry to switch bodies. As Candace is bedridden, she asks Stacy to be in charge of busting her brothers who are attempting to build a huge miniature golf course.
As Candace finds out that a traffic camera DVD in the neighborhood has recorded proof of her brothers' mischief, Agent P sets out to destroy it. The boys attempt to build the world’s largest bowling ball and pinball table.
During a storm, Grandpa Reg tells the kids a story about Ferb's ancestor, Ferbgor, while Dr. Doof tells Perry the story of his ancestor, Jekyll. The boys help their friend Django to make his artist father Beppo realize how talented he is.
The boys lend Baljeet a hand with his science fair project, as they help him build a portal to Mars. As Candace feels neglected by her friends, she ends up being stranded on Mars after the portal breaks.
As a meteor shower is about to hit Danville, the whole town becomes obsessed with stars, including Lawrence Fletcher who buys certificates online to name stars after the boys and Candace. The boys build a rocket to travel into space.
As Isabella argues with Buford to prove to him that girls are better than boys, Phineas and Ferb come up with a sports challenge to determine who is better. As the boys carve pictures of their faces into a comet, Candace attempts to hang out with Jeremy, but his sister tags along with him.
The boys decide to create a cartoon with them as superheroes, while Dr. Doof creates an invention that makes people dance uncontrollably. As Vanessa tries to bust Dr. Doof, the boys invent a machine for Isabella that creates rainbows.