Finn is in the tree house and calls out to jake or beemo, no one responds so he thinks theyre not there and pulls out a lock of hair from under the couch the lock of hair is from bubblegums hair then jake and beemo appear and Finn quickly tries to hide the lock of hair and jake and beemo tell Finn that they already know his "secret" and jake tells him that everyone has their own keep sake jake shows him his blanket as an example then a "door lord" appears from a door and quickly takes Finn's lock of hair along with jakes blanket and beemo's plug they quickly chase him while he throws keys that magically open doors which transport you to another place. Finn and jake along with beemo keep going through door after door along the way the door lord also takes a little candy boy's train and Finn oddly says "ill save your kid toy train" and go into another door leading to princess bubble gum's room and she follows them aswell then the also run into Marceline and she follows them as well. They finally arrive to a narrow valley and the door lord enters a large door which appears to be different than all the others they were in. The door slams shut and Finn and the others aren't able to enter then around the door shines in gold what they must do to open the door they must sing a song to the door which is oddly made out of what appear to be tiny faces with eyes and mouths, Finn decides that they should make a band which starts of very badly because Marceline and Princess bubble gum don't like each other that much but appear to have had a friendship in the past. while they are fighting Marceline starts singing a sad song which makes the faces on the door open their mouths and start to light up. They look like they are enjoying the song until Marceline starts to miss the song and the faces start to close their mouths. She gets angry and says that Princess bubble gum threw her off. in their band Finn makes the beats jake plays his viola Marceline plays he Axe-base and Princess bubble gum opened up beemo and made used him as an electric instrument. Finn tries to keep them together, they take a "noodle break" and continue at some point Finn says they should make a noodle song but everyone didn't like the idea. After that they are still trying to figure out a song then Princess bubble gum gets an idea for a song and tells everyone to play certain notes and draws a equation in the dirt then she accidently shortcircuts beemo and Marceline tells her shes not as smart as she thought which results in them fighting and leaving the band jake pretends to leave the band too because he mentioned before that he wanted to be the jerk in the band Finn is very depressed and starts singing a song about his friends and they all come back to help him finish it which makes the door finally open and they go in to and find the door lord sitting in a room filled with filing cabinets eating a sandwhich he then makes symbols which to Finn make no sense but Marceline understands him and says that he means that he took their stuff in order to show them how friendship is more important. He still gets beat up and jake hands out everyones belongings: Finn's lock of hair, beemo's plug,Jake's blanket and Princess bubble gum's shirt. Then Marceline looks at Princess bubble gum's shirt and was surprised that it was the shirt she had given her which was probably in the time of their friendship. Princess bubble gum says she still wears it, but only as pajamas. after that Finn points out that Marceline didn't have anything missing and tells her that she probably just wanted to hang out which makes her a little upset so she turns into what looks like a giant zombie and chases everyone out while they are all laughing.
I know my summary is bad and I wrote this fast im very sorry I know there are alot of details left out but it was just a summary I will make something more accurate in the future. Thanks for anyone reading this please tell me if it was at least any good.