It is spring break and Scrooge and the kids are at a hotel, the Conquistador Inn, which happens to be located near The Fountain of the Foreverglades. Annoying Dewey, Huey has a whole day planned out for their vacation stay. According to Dewey, Huey always has charge, because he's the older brother, leaving him jealous. Scrooge and Webby later run into Goldie O'Gilt, who happens to be at the hotel, too. She claims that she is after the fountain as she snatches Isabella Finch's book from Scrooge and disappears into the jungle, while Scrooge and Webby follow her.
Dewey attempts to dive in the pool, however, all the teenaged Spring-breakers fill the pool, ruining the fun for him and leaving him disappointed. A little while after their relaxation period, Dewey appears to be taller, much to Huey and Louie's shock. This pleases Dewey, because he claims himself as the oldest triplet, and attempts to create a schedule of his own. Afterwards, they notice that the Spring-breakers are gone and that there are only elderly people.
Back in the jungle, Goldie reveals that she stole some water from the hotel, to which she and Scrooge fight over. Because of this, they fall into a river. After being submerged in the water and coming back out, they've turned into teenagers restoring their youth.
As they continue to follow along with Webby, they flirt and agree to use their youth as a fresh start in their lives with one another and seek to use the fountain to remain young. While walking, Webby gets into several mishaps, such as body aches and being attacked by mosquitos which, ironically, lead her to feeling old. When they arrive at the fountain, they find an elderly Rockerduck strapped to his henchman, Jeeves, the former revealing he spent millions on experimental freezing technology, which was somewhat successful. They fight over the water, realize it's gone, and conclude that it must be back at the hotel.
As Huey and Dewey continue to argue over who's the real older triplet, Louie finds the manager, Ponce de Leon, with all of the water that contains youth after he put two and two together. Leon then captures the three in a floatie and locks them in his manager room which contains several jugs of the youth water. He explains that the fountain does not restore youth but rather transfers it from one person to another, so he sacrificed his own crew by throwing them in the fountain draining their youth so he can have it for himself, but over the past 500 years it was getting harder for Leon to lure people in so he diverted the water from the fountain into a pool and built the resort around it to lure in unsuspecting teenagers. Dewey then comes up with a plan to chew on the floatie and pop it, which turns out unsuccessful. Scrooge, Goldie, Rockerduck, and Jeeves arrive at the inn to battle Leon. During the fight, Rockerduck drinks some of the water and restores his youth, however, is knocked unconscious by Scrooge. At the same time, Goldie sneaks into the manager room to steal some of the water, but when she sees Louie in peril, she returns back to Scrooge. She then defeats a furious Jeeves by forcing some water into his mouth, which turns him into a baby as Rockerduck carries him and leaves.
Soon after, Leon drags Scrooge into the pool, strangling him and causing the later to slowly lose his youth. Goldie then rescues Scrooge as they swim to the surface, now with both of their youth lost. They watch as Leon's youth is drained out, wrinkles, and dies in the pool.
The boys roll out of the room and the floatie pops. They then serve the youth water to the elderly Spring-breakers, which restores their youth as they run back to the pool. Dewey then realizes that being an older brother can be a handful and apologizes to Huey, then he has one drop of the youth water, restoring him to his normal age. Scrooge surprised at how Goldie sacrificed her youth for him, she then remarks how her youth wouldn't matter without him. She returns the journal just before grabbing and kissing him. She then yells "Spring break!" as everyone cheers.