since Phineas has Isabella, Ferb should have a girlfriend too (and pairing him with Vanessa Doofenshmirtz wouldn't work in the long term since she's about seven years older, and she already has a boyfriend)
Phineas and Ferb build a 나무, 트리 house and remodel Candace's old one. Later, they get in a 나무, 트리 House Fight against Candace and Stacy. Meanwhile, Perry tries to stop Dr. Doofenshmirtz from getting revenge on his brother Roger.