Vanessa once again tries to talk to her father, but he too busy once again making improvements to his traps.
Isabella suddenly looks at the triangle-headed boy and all the memories of her secret crush come back to her. The gang make their return to the backyard, but the inator lands on the far side of the fence.
Candace once again tells them the situation of her missing brothers. She also adds that the internship is something she really wants to do, and that she feels unhappy living in the Tri-Govenor's Mansion.
He tells Norm to "stuff it", so Norm eats the cake himself. They once again attempt to run up to the inator, but their time loop isn't long enough. (Song: "Serious Fun") Chorus: ♪ Doo-doo-doo-doo ♪ ♪ Doo-doo, doo-doo-doo... ♪ Phineas: ♪ Get out your tool case, ♪ ♪ Put on your game face. Isabella suddenly looks at the triangle-headed boy and all the memories of her secret crush come back to her. Perry escapes that trap as well and immediately hits the self-destruct button on the Tri-Governor-inator.
Suddenly, the time loop begins at the point where Doof and the others finished the inator.
A 73-hour marathon of … On the inevitable 104th day of summer vacation, the season — and the series — is quickly coming to an end, and it’s Candace’s last chance to bust her brothers; who build huge playground equipment for the finale of summer.
As such, Doof rambles on about the risks of the Time-Straighten-Out-inator.Doofenshmirtz, Vanessa and Perry finish the inator faster than before.
Agent P arrives at DEI and immediately gets trapped in the bass drum of Norm's drumset. Buford then sees the Do-Over-inator, but Candace inadvertently reveals what it is. Doofenshmirtz explains to his nemesis that he realized that his goal of ruling the Tri-State Area was all for naught since it turned out there was no such position. Meanwhile, Phineas and Ferb decide to distract the tigers by giving them a giant ball of yarn made of all the suspenders and Capri pants. Her father explains that 45% might bring about wiping everything from existence. Candace once again walks into the kitchen but then notices her parents both lapping at their cereals. Despite this, Doof states that as long as the Do-Over-Inator is activated, he will still find a way to defeat Perry.
Doof also proclaims that he will send Perry a bill for burning the carpet with his jet-pack. He asks Norm for some muffins, but Norm is confused because he does not know what a muffin is, which made Doof realize that the effects of the Do-Over-inator creating time rifts in the space-time continuum that can erase anything from existence. This time, she attempts to avoid the roller skate, but still manages to slip onto a third roller skate and once again fall down the stairs.
Phineas shows the gang a massive blueprint.
Lawrence shrugs it off and laps at his cereal like a dog. ♪ Phineas: ♪ We've got one last day of summer, ♪ ♪ One more day before school has begun, ♪ Phin… Candace wakes up from her bed a third time and realizes the day is once again repeating itself.
Vanessa helps her father realize that despite his newfound success as Tri-Governor, he is terrible at being an "evil" scientist.After finishing up his work schedule as Tri-Governor, Doof returns to Vanessa's suite, where Vanessa finally tells him about the internship and that she still has to move out. Buford wonders if it really is worthy of a grand finale. Candace then starts to suspect that something is going very wrong. Phineas and Ferb is a show that I have watched with my family. Vanessa sees Perry moping over his failure and reveals her true reason why she's moving: she was accepted into O.W.C.A. Perry, not really believing his frenemy, reluctantly provides his assistance. In a rather gray and colorless void that resembles Danville, Phineas and Ferb are wandering around and taking in their surroundings.
She discovers that they do not know what a spoon is nor what tigers are. Doofenshmirtz explains to his nemesis that he realized that his goal of ruling the Tri-State Area was all for naught since it turned out there was no such position. She finds herself reciting along with her parents, but they laugh it off as a philosophical thing. Perry escapes that trap as well and immediately hits the self-destruct button on the Tri-Governor-inator. When Candace enters the backyard, she tells the gang she is going to bust them "out of this world", which brings further inspiration. Candace walks into the backyard when the gang reveal the blueprints and tells them this time that she will get her mom instead of calling her. Without hesistatation, Candace activates the -inator, and a bubble appears surrounding herself and Doofenshmirtz. "Since it's our last day of summer, we're thinking a grand finale is in order!" Doof tells the others the 55% of chance will lead to success, but Vanessa wonders what the 45% entails. Meanwhile, Doofenshmirtz talks to Vanessa about her intent to move out and shows her the news of himself being elected as the new Tri-Governor, much to the horror of his younger brother Candace runs to the backyard and asks her brothers to help her. The rifts appear and cars begin to fall out of the sky. But Vanessa is aggravated that her father is not listening and tells him she is permanently moving to Upon hearing of Vanessa's last words being recorded by Norm, Doofenshmirtz jumps to the conclusion that Vanessa is moving out simply because she thinks he is a loser.
She goes to her mom to tell her what happened, but Linda is confused because she has not heard of anyone named "Phineas" or "Ferb". This time, Candace practically pushes her mom out the door.
Though Vanessa somewhat admires the new features of the suite, she tries to tell her father the true reason why she's moving out.
Perry gets trapped in the bass drum again, only this time, he rolls past Norm's drum set, escapes, and gets trapped in a giant skull. Doofenshmirtz once again wakes up, but this time, he avoids the lamp. Candace gets the device Baljeet was measuring the space-time continuum with and gives it to him.