Phineas and Ferb end up in the Land of Ooo because of there transport machine. They get stuck there and have to find a way out.....
Transcript[]
(On a normal summer day Phineas and Ferb wake up)
Phineas: I wonder what's its like to be in somewhere that creatures live in.
Perry: (Chatters)
Phineas: Ferb, I know what were gonna do today! Hey, where's Perry?
(Cuts to lair)
Monogram: Good morning Agent P. I don't really know what Dr. D is up to, but you better stop.
Perry: (leaves)
More coming soon....