The boys learn about one of Ferb's Victorian ancestors, who helped a scientist create a monster. Meanwhile, Doofenshmirtz recalls the story of his great-great-grandfather Dr. Jekyll Doofenshmirtz.

When Django feels down for not being able to draw art on the same scale as his father, Phineas and Ferb get some big ideas for his piece and the famous "unpainted desert". Meanwhile, Perry faces off against Doofenshmirtz, as he does his best to impress his visiting evil professor.

Candace switches places with a princess who looks exactly like her, while the real princess helps the boys build a giant jukebox filled with live bands.

When Linda and Lawrence go on a trip, Candace decides to have an Intimate Get Together with Stacy and Jenny. But, then more people come and makes it into a party. Later, when her parents get home, Candace gets busted.

When Candace discovers that Phineas and Ferb have invented a computer that can answer anything, she asks it how she can finally bust her brothers once and for all. Meanwhile, Dr. Doofenshmirtz loses the key to his latest invention, the "All Purpose-inator," and Agent P must find it before he does.

Perry misses his 100th battle against Dr. Doofenshmirtz when Candace takes him to the Charity Pet Wash with her. Perry's absence goes unnoticed when the zookeeper's typical platypus at the Danville Zoo stops Dr. Doofenshmirtz's plan to zap his brother with his "Least Likely-inator." Meanwhile, the boys build a fun house Phineas and Ferb style.

Phineas and Ferb create their own language, Ferb Latin, which quickly catches on. Unfortunately for Candace, she awakes from a massage puzzled to find everyone else speaking a language she doesn't understand. Meanwhile, Dr. Doofenshmirtz decides to use propaganda as his new "-inator," believing that it will work since people will believe anything they read.