The Great Indoors-Bad weather spoils Isabella's plan to earn a Fireside Girl patch, so Phineas and Ferb build a huge bio-dome to help her. Meanwhile, Candace works herself into a frenzy when she decides that she needs to find out what Jeremy likes about her. Over at Doofenshmirtz Evil Inc., Dr. Doofenshmirtz is trying to rain out a big soccer game, just so he can watch his favorite Mexican soap opera.
Canderemy-Candace realizes that she needs to spend more time with Stacy, so she vows to spend the whole day with her only. But while visiting Jeremy and his mom, Mrs. Johnson (voiced by Jane Lynch), Dr. Doofenshmirtz’s “Combine-inator” zaps her and Jeremy, literally joining them at the hip. Meanwhile, Phineas and Ferb build a giant robot dog which causes a lot of mischief.