Phineas and Ferb are thinking about todays activity when Isabella and Baby Ana come over. Isabella tries to help them decide while Ana goes over to play with Perry. Perry goes behind the house to enter his secret lair unaware that Ana is following him. When Major Monogram sees Ana he thinks she is a secret agent. Monogram tells Perry that Dr. Doofenshmirtz has bought mechanical equipment for unknown reasons. Perry sees Ana in his jet, and tries to save her, but Ana turns on the ignition while Perry is on the tail wing. When Phineas and Ferb realize that Perry is missing once again, Isabella realizes that Ana got lost too. Phineas decides that today they'll make a giant rattle to attract Ana. Meanwhile Ana is still flying the jet with Perry still on the tail wing. The jet crashes right into Doofenshmirtz' building, Perry lands flat on his face while Ana lands safely. Doofenshmirtz wonders where the baby came from, but assumes her as no threat, he puts her on his lab desk while he traps Perry in a cage. Doofenshmirtz explains that in his childhood he was always picked on because he was smaller than everyone else, and when his baby brother was born he had a chance to pick on him because he was smaller than him, though Doofenshmirtz still couldn't forget his own constant bullying so he invented the Baby-inator so he could turn the entire tri-state area into babys he could pick on them for they're size. Perry tried to get out of the cage with a nail filer, but it would take a while. Phineas and Ferb finished the giant rattle complete with a gint mechanical arm to hold it. Isabella told Phineas to hurry and she was worried about Ana. Phineas moved the arm and it started to shake the rattle. Back at Doofenshmirtz' lair while Doofensmirtz was monologing Ana saw the rattle outside and crawled to the window. While trying to grab it Ana accidentally hit the joystick and the Baby-inator turned it's aim on Doofenshmirtz. When Doofensmirtz finally pressed the button the beam hit him and turned him into a baby, who curiously was smaller than Ana. Doofenshmirtz looked up at Ana and cried. Perry finally got out of the cage and took a battle pose only to see Ana defeated Doofensmirtz. Ana smiled at Perry and Perry smiled back. He got back on board the jet with Ana in the back, and went home. Phineas, Ferb and Isabella get worried and decide to give up when Perry and Ana come back. Isabella picks up Ana and heads home. Ana looks at Perry and says his name. Perry smiles and blushes.
Isabella holding Ana.
After Ana says Perry's name, " I wonder what my first word was."