Ep 3. Sidetracked

When Perry the Platypus disappears while on a mission, Major Monogram assigns Agent P's duties to Peter the Panda. Unbeknownst to Peter, Doofenshmirtz has taken Perry captive in order to use him to power his Ultimate Evil-inator. Meanwhile, Phineas and Ferb set out on a train ride to the big city to see their favorite band in concert, but things take a turn when they accidentally board the wrong train and end up in the middle of Doofenshmirtz's plan. With the help of a girl named Isabel, they must find a way to stop Doof and rescue Perry before it's too late. Along the way, they encounter a new villainous duo, who are also after Perry. Will Phineas and Ferb be able to save Perry and make it to the concert in time? Find out in "Sidetracked."