Doofania is the city-state created by Dr. Heinz Doofenshmirtz with help from his robotic assistant, Norm, so he did not have to live in a place disturbed by his brother Roger and his ex-wife Charlene. He built it so that it floated on the water on an innertube. Before he built the actual "country," Doofenshmirtz made a plush model because he had a lot of felt handy. It was destroyed when Phineas and Ferb fired their Rainbow-inator. A boat full of fishermen in the harbor saw the rainbow, and one of them was so distracted he cast his line onto the inner tube that Doofania was floating on, sinking it to the bottom of the harbor. Minutes later, Doofenshmirtz and Norm resurfaced, soaking wet.
At Doofenshmirtz Evil Incorporated, Heinz readed in the newspaper that his brother Roger had been elected mayor of Danville. Upset at the prospect of having his honest, reputable, law-abiding brother as mayor, he told Norm he knew what they were going to do that day.
Meanwhile, at the Flynn-Fletcher house, Phineas and Ferb were eating Fruity Rainbow Flakes cereal. Isabella came in and asked what they were eating. She took a look at the box and held it up and told the boys she was never actually seen "one of these" in real life. Phineas knew what he and Ferb were going to do today. Linda walked in carrying Perry. He was missing patches of fur and had a pet cone around his head to prevent him from licking his wounds like dogs and other animals normally would. Phineas asked why Perry was wearing a satellite dish, but Linda explained that it was a protective collar and he had to wear it for the rest of the day because he was scratched himself up so badly. Perry remembered a fight he had with Doofenshmirtz on a rooftop, as the evil doctor was attacking him with an umbrella. Perry lost his balance while attempting to avoid the umbrella and landed in a sandpaper factory, which took off several of his fur patches. This also allowed Doofenshmirtz to escape victoriously, much to Perry's dismay.
Phineas thought it was a bold fashion statement. Speaking of bold fashion statements, Candace was making one of her own. The dry cleaners mixed up her clothes with some goth chick. Screaming, she called her mom in and complains that she looked all "outsidery".
Back at Doofenshmirtz Evil Incorporated, Vanessa Doofenshmirtz was on her cell phone to her friend Lacie complaining about getting her clothes mixed up, too. She thought she looked like a walking candy cane. All of a sudden she heared power tools in the next room and went to investigate. Dr. Doofenshmirtz was sitting on a girder using a drill. Norm came over to ask what he was doing and Doofenshmirtz explained that he was building his own evil empire. Vanessa bursted in and demanded to know what was going on. After noticing what she was wearing he revealed his plan to her. They were going to be moving to a golden country on the sea, created by him and assisted by Norm. He showed her the model he built, explaining that he would be the ruler of his own empire, where there would be no brothers trying to make him look bad. She had a revelation: She would finally have proof that her dad had evil schemes, though it was obvious that building his land couldn't be considered as evil. Heinz hoped that it would be a special father-daughter bonding experience. Instead, Vanessa went back into her room to call her mom, Charlene, but she didn't want to hear about it since she was having her "me day." She would pick Vanessa up when she was done at the spa.
Meanwhile, Phineas and Ferb had finished their creation, but wondered where Perry went. Turns out, Perry was having a hard time getting down into his lair with the cone on his head. Major Monogram was already on the communications device and wondered where he might be. He even checked with Carl to find out if Agent P knew that there was a call scheduled. Carl informed him that it was on his calendar. In the backyard, Isabella came over to see what Phineas and Ferb were up to. They reminded her that she said she had never seen a rainbow before, so they built a Rainbow-inator made with real crystals and supercharged by Fruity Rainbow Flakes. Soon there would be a giant rainbow sprawling across the entire Tri-State Area! Several times during this explanation, Isabella tried to tell Phineas he was wrong about something, but he was not listening to her very well.
Linda and Candace had gone to Seeds, Weeds and Wackers to return a novelty jackalope lawnmower that her husband had purchased. Linda made Candace hold the door for her even though the teenager didn't want to be seen in the goth clothes she was wearing. Just as she feared, Candace got spotted by her rival Mindy who took her picture with her cell phone and sent it off to all the kids in school. Within seconds of the picture being sent, Stacy called her and asked why Candace didn't tell her she was goth now. Moments later, Jeremy showed up and was a bit shocked by her clothes. She stammered out some sort of an explanation, then asked if he liked them.
Down at the docks, Norm and Dr. Doofenshmirtz were launching their creation, but the scientist had a moment of melancholy when he realizes his nemesis hadn't shown up to try and stopped him. Vanessa, on the other hand, was still trying to get her mom to come to the harbor to see what her father is up to. Charlene promised to meet her at "FEH", but Vanessa had no idea what she meant.
Confused, Vanessa hanged up her phone and a giant inner tube floated up behind her. A massive sheet came off the top, revealing the life-size version of her father's model. It was labeled "Doofania" on a huge banner. Doofenshmirtz greeted his daughter and he and Norm sang the Doofania national anthem. Just then, Charlene arrived at FEH, as promised. Turns out FEH was the Freight Emergency Harbor. Vanessa dragged her mother over to where Doofania was floating in the harbor.
Over on Maple Street, Phineas and Ferb were about to fire up their Rainbow-inator. Phineas mentioned Perry again, who still could't get into the entrance to his lair because of the cone around his neck. Ferb fired up the contraption and Isabella poured in some Fruity Rainbow Flakes cereal. The device launched its rainbow across the sky and distracted some fishermen in the harbor.
One of the fishermen casted his line and got his hook stuck in Doofania's inner tube. Reeling it in caused a hole to break open and deflated the inner tube, sinking Doofania into the harbor just as Charlene and Vanessa arrived to bust Heinz. The only evidence left was the small felt plush model of Doofania that Doofenshmirtz made.
Charlene found it absolutely adorable and took it home with her. She also dragged an upset Vanessa home to get her out of the sun. Doofenshmirtz was very upset and took it out on Norm. When he asked who wanted to play lawn darts, the evil scientist said he would rather play hide and sought because he didn't want to see Norm.
In the Flynn-Fletcher backyard, Perry was still trying to get through the door and into his lair. He hited his cone so hard, he bounced off the side of the house, through the backyard and into the Rainbow-inator. This launched a self-destruct sequence and it vanished with a puff of smoke. Perry fell on his back, then a butterfly entered his cone. Perry sneezed, then Phineas blessed Perry in a Doofenshmirtz-esque manner.
Moments later in Perry's lair, Major Monogram was still on an open channel. He was singing Gitchee Gitchee Goo and was upset when Carl tried to join in.
Phineas asked Isabella what she thought of her first rainbow. She admitted to him that while it was a nice rainbow it wasn't the first one she'd ever seen. What she meant at breakfast was that she had never seen a unicorn, not a rainbow. Phineas knew what they were doing tomorrow. Perry chattered at him, and Phineas realized it was the end of the day and he could take the collar off.
Perry quickly jumped up, put on his secret agent hat and headed down to his lair. He got his assignment and headed off to the harbor. Norm and Doofenshmirtz were playing hide and seek. Norm wasn't very good at it. Suddenly, Perry bursted in and landed in front of Doofenshmirtz, but the latter was unimpressed by this and sarcastically told Norm, "Look who decided to SHOW UP!!" This left Perry extremely confused, wondering if he had missed Doofenshmirtz's scheme again or not.
Downtown at the Dry Cleaners, Linda and Candace were inside trying to fix their mix-up. Vanessa then walked in, feeling really upset that she had failed to bust her father again. Candace and Vanessa slowly turned to each other, realized what had happened, pointed and said, "Hey!".
- Doofania's buildings took the same shape as Danville's buildings. For example, the Doofenshmirtz Evil Inc. building was also in Doofania most likely as the capital or the country headquarters.
- It had its own anthem to go along with it but it cutted off a little short.
- In the anthem, Doofenshmirtz stated that was "founded on spite".
- The whole city-state floated on an innertube.
- It remained unknown if Doofania's innertube or felt had been recovered or not from the ocean floor.
- The country was for "Me and me" (Doofenshmirtz).
- He built the entire city in one day, much like the Big Ideas that the boys make.
- The way Doofania raised in the air and slipped under the waters was similar to how the Titanic ship sunk in 1912 in a similar fashion.