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.

Inspired by Dad's favorite childhood program, the boys decide to create a magic carpet, and Candace is convinced that fortune cookies will lead her to bust her brothers. Meanwhile, Dr. Doofenshmirtz plans on ruining his brother's art unveiling by using his "Stain-inator" to ruin a mysterious painting, but as it turns out, the painting is Dr. Doofenshmirtz's very own masterpiece that he created when he was a youth back in Gimmelshtump.

Phineas and Ferb build a giant version of a favorite childhood game, with Danville as the central location. Meanwhile, Doofenshmirtz takes Vanessa on a camping trip.

When Phineas and Ferb are inspired by an antique escape chamber that Dad acquires, they decide to build a computer-controlled tower that will trap them inside and allow them to explore the world of escapement. Meanwhile, Dr. Doofenshmirtz invents a "Rude-Inator" to ruin Roger's meeting with a visiting dignitary from England.

In ancient feudal China, Princess Isabella is part ruler and Master Perry has given up the way of the warrior. After Phineas and Ferb witness Doofus Khan capture the Princess and take her as a prisoner, they track down Master Perry and convince him to teach them his warrior ways so they can rescue Princess Isabella and save China.