Dennis, a rabbit agent of the Agency gone rogue, uses Candace's fondness for him as a pet as a way to infiltrate Perry's headquarters and hack the Agency's mainframe. Meanwhile, Phineas and Ferb develop actual X-ray glasses after being ripped off by a novelty variety, and Doofenshmirtz creates a new impromptu nemesis out of a potted plant due to Perry's absence.
Candace and Stacy become sidetracked from a scheduled spa appointment after going to a volunteer house building project simply because Jeremy was there, so the two get their service from a spa built by Phineas and Ferb. Meanwhile, Doofenshmirtz's new pet cat Mr. Fluffypants creates chaos at his lab.