This is a special and is not part of any season!
Phineas and Ferb are lying on their beds looking at the cieling. Ferb says, "Phineas, I know what we're going to do today! Read!" They both pull out some books from under their beds and start to read them. Ferb has a mystery book and Phineas has a book of magical objects. "Hey Ferb, look at this!" Ferb gets off his bed and walks over to Phineas. Phineas points at the second page. "It says that the Stone of dreams will grant it's finder, one wish! But it's in the underworld, how could we find that? Ferb, I know what else we're going to do today, we're going to build a portal to Mars that can also go to other places! Wait, we already did that!"
Baljeet opens the door after hearing a knock. "Baljeet, do you still have the portal to mars blueprints?" "Yes, here you go!" Baljeet gives Phineas the blueprints and closes the door. A truck pulls into the driveway of Phineas and Ferb's house. A man climbs out. "Delivery for Phineas Flynn!" "That's me!" "Aren't you a little young to build a portal to Mars and use it to go to the underworld and find the Stone of Dreams?" "Well, I don't think so!" "Good enough for me." The man pushes a big crate into the back yard. An hour later...
Okay, opening portal in 5... 4... 3... 2... 1... Opening now!