Phineas and Ferb create a device to reverse the effects of gravity. Meanwhile, Major Monogram believes the boys are out to destory the tri-state area, so he sends Carl to the Flynn-Fletcher house to investigate, while Agent P is literally sent on a wild goose chase to find a long-lost agent. Elsewhere, Doofenshmirtz finds the blueprints to Phineas and Ferb's anti-gravity machine and takes them for his own evil purposes.