Dr. Doofenshmirtz mentors a young up and coming evil scientist, unaware his student has sinister intentions. Luckily, Agent P. has backup in the form of Monty Monogram, his boss' son!
Meanwhile: Phineas and Ferb decide they can't wait until autumn to jump in a pile of leaves, and create a giant leaf pile to celebrate "S'Fall".
- All Girls Want Bad Boys: Vanessa, which she blames on having an evil dad that she loves. At the end of the episode, she decides to drop it and give good guys, namely Monty, a try.
- Comically Missing the Point: Candace spends most of the episode convinced the boys' project is merely hidden in the giant leaf pile, and not that the leaf pile itself is the project.
- Eviler Than Thou: Rodrigo to Doof. He wants to destroy the Tri State Area, take over the world, and will kill Heinz and Perry to do it. He also upgrades Heinz's trap to one Perry cannot get out of without help.
- Oh, Crap!: Perry's reaction both when Rodrigo reveals his real intentions and when he realizes Vanessa may like Monty.
- Too Dumb to Live:
- Rodrigo thinks that just because he had "a moment" with Vanessa, she'd betray her father for him. Vanessa angrily lampshades this to Perry.
- Vanessa herself, when she puts on her father's boot trap as a shoe while forgetting it's stuck to the floor, which forces her to sit out the climax.
- The Unreveal: Played for laughs, Buford claimed the gourd helmets he made for everyone capture their essence. When Isabella asks how hers does that, Phineas claims it's obvious and assumes she must be kidding.