As Phineas Flynn and his stepbrother Ferb Fletcher embark on a quest to create grand inventions, their controlling older sister Candace sets out to bust them, while their secret-agent pet, Perry the Platypus, is on a mission to thwart the evil plots of the mad scientist, Dr. Heinz Doofenshmirtz.
In season 3, Phineas and Ferb embark on new adventures, including the boys building a biodome to help the Fireside Girls, and Candace using boots invented by Phineas and Ferb to be in two places at the same time.
In Season 4, Phineas and Ferb invent a giant new gadget; Buford fiddles with wires and creates a ray that turns Candace into a fly; and Candace embarks on a perilous adventure in an attempt to get back to the boys.