Phineas and Ferb Christmas Vacation!

On Christmas Eve, Lawrence and Linda are waiting at the airport for Lawrence's parents to arrive from England. The scene sets the stage for the holiday setting and family reunion, emphasizing the anticipation and festive atmosphere. Meanwhile, Candace is preoccupied with finding the perfect gift for Jeremy.

Phineas and Ferb convert the top of their house into an extravagant rest stop for Santa Claus, featuring a sauna, massage table, satellite TV, and reindeer feeding center. They encourage the citizens of Danville to help decorate the city for Christmas, spreading cheer throughout the town. Candace dismisses the boys' Christmas enthusiasm as childish.

Perry the Platypus sneaks off to a Christmas party hosted by OWCA and receives an emergency alert about Dr. Heinz Doofenshmirtz's evil plans. He heads to Doofenshmirtz's lair, where he finds the scientist planning to use the 'Naughty-inator' device to ruin Christmas and declare everyone in Danville 'naughty'.

Doofenshmirtz activates the Naughty-inator, causing Santa's workshop to brand everyone in Danville as 'naughty,' canceling Christmas in the town. Phineas, Ferb, and their friends are distressed by the loss and try to find a solution to save the holiday.

Two elves, Blayn't and Clewn't, arrive from the North Pole and inform Phineas and Ferb that the city itself, not just the residents, is 'naughty.' They are unsure why this happened, leading to a need to undo the misclassification and restore the Christmas spirit.

Doofenshmirtz plays Sal Tuscany's Christmas song on his stereo, which vibrates and destroys the Naughty-inator, lifting the 'naughty' label from everyone and restoring Christmas cheer to Danville. The elves confirm it is too late to fix the mistake with Santa.

Phineas, Ferb, and their friends build a flying sleigh with help from the elves, intending to deliver presents to every house in Danville. They face challenges in the dark but successfully deliver gifts, with Buford turning on the city lights to help.

Perry manages to trap Doofenshmirtz in his own Christmas lights, ending his evil plans and giving him the ability to hate Christmas, which he surprisingly takes in stride. Perry's intervention helps restore the holiday spirit in Danville.

Santa arrives in Danville after finishing the delivery of presents and thanks Phineas for helping with the holiday. He leaves with a fully decorated rest stop hitched to his sleigh, spreading joy throughout the town as he departs.

Doofenshmirtz discovers that the gifts and plans he received from Santa were actually from Santa himself, revealing that the 'Y' in 'Sal Tuscany' is an anagram for Santa Claus. He realizes that Santa's plan may have been to help him find holiday happiness.

Candace sells her necklace to buy Jeremy a new guitar, while Jeremy sells his old guitar to buy Candace earrings. Their exchange symbolizes the spirit of giving and love during Christmas, concluding their ongoing romantic storyline.

Lawrence and Linda return from England with the children’s grandparents, completing their family reunion. The town enjoys opening gifts, including a special present from Perry to Doofenshmirtz, symbolizing friendship and holiday cheer.