One morning in August, Candace wakes up and opens her computer. She reads an e-mail from Stacy. The email says it is holding an evening party at the new club that just opened in Danville, Candace knows what's going to do today and will re-send the mail to everyone who has added the messenger: Stacy Jeremy, Jenny, Coltrane, Chad, drummer nameless, Vanessa, Lacey, Johnny and the other punk, the two young men who sang SIMP among other teens
Phineas and Ferb find out the news and ask that they are too young to go to a party at a pub, if they can mount a house party for her friends and her mother leaves them, after that, Phineas asks where is Perry, immediately afterwards, this is displayed by entering their lair through a sewer, where it enters the den, out for a toilet and it is to Major Monogram in the shower singing "Yodel Odel Obey Me", Monogram is surprised and says that if you can wait out a shower to get a mission, immediately afterwards heard noises from outside the bathroom and a voice says: "Sir, stop", the camera focuses on Carl jumping in front of the bathroom door with his legs crossed and jumping, "Sir, takes half an hour in the shower and I'm peeing," says Monogram Doof Perry that Johnny has been cited in your building for something of a party, then asks Carl because he's not going to the party and tells Carl that quire like to go to the North Pole but please let him to enter.
In the garden of the Flynn-Fletcher, Phineas and Ferb end their pub just before reaching Isabella, Baljeet, Buford, Irving and Django, to their astonishment, they discover that the place built by Phineas and Ferb is so good that everyone Danville has decided to conduct the festival there.
Then focus on building Heinz Doofenshmirtz, Perry walks through the door and Dr. Doofenshmirtz gets caught in a wine bottle size and tells Perry he has a problem, immediately afterwards, the doorbell rings, it is Johnny who appears wearing a suit and tie, his hair slicked back, it seems he then heard a heels, Vanessa leaves her room with a ball gown "word of honor", the dress is black leather with high heel shoes, Her eyes and lips painted, in this scenario looks at the couple Perry and Doofenshmirtz and then laughs as the doctor does not know what to do.
Candace and Stacy finished arranging for the night, Candace has the same dress he wore in "Chez Platypus", as to Stacy, she painted her face and put on a frilly dress (similar to Vanessa) but blue sky, Jeremy (dressed as "Chez Platypus") and Coltrane (dressed like Jeremy) go to pick them up, both hold hands with their partners.
back to "Doofenshmirtz Evil Inc.", Heinz tells Vanessa Doofenshmirtz go for some keys, when Vanessa goes, Doof press a button trapping Johnny in a chair, then, Heinz encience his "lantern-inator" and starts to question him about where Johnny is going to take her "baby," Johnny tells plan Doof night and scared, when Vanessa is approaching, Doof unleashes Johnny and the couple leaves, Doof more angry looks at Perry, he makes a half smile but Doof faces him away.
Phineas and Ferb are the most successful bartender of the party, in collaboration with Buford, Baljeet and waiters company as the party has been a success, while he still has Doof Perry fears about the dinner, when he sees his brothers Candace sees Phineas and Ferb and gets angry and says she will call her mother but Stacy and Jeremy try to relax her.
Doof is still angry and continues monologuing about the problems of modern society and how life was better as a lawn gnome, then Doof thinks in a idea, He will use his old "Gnome-Inator" to turn Vanessa into a gnome, she would look horrible and Johnny would let her, so Doof will show Vanessa that he always loved her for her physicall appearence and...then Perry makes a sad face and Doof says that it's bad doing that and not bad in the sense of evil, Doof says, but he has the inator so he fires it up for seeing only what it does, it turns into a gnome the restaurant that runs away before Linda and Lawrence can see it.
In the end credits, the couples dance to the music of the dance hall: Phineas and Isabella, Ferb, Baljeet and Buford, Django and Irving, the Fireside Girls, Stacy and Coltrane, Monogram and Carl, Doof and Perry and, infront of them, Johnny and Vanessa, Vanessa looks at his dad embarrased and Johnny tells her that it doesn't matter and Johnny starts dancing with Doof