Finn and Jake go to Marceline's house to jam, but she is leaving her house when they get to it. They ask where she is going and she says she is going to visit a friend in rainbow kingdom. Jake says that he has heard about the place from Lady Rainicorn. Finn and Jake follow Marcy to a portal and go through, and then Marceline leads them to her friend, Rainbow Princess. Rainbow gives them a tour of her kingdom before one of her staff from the castle tells her they need her. She tells Marceline to finish the tour and tell them about the history of the Rainbow Kingdom. Jake says to Marceline that he already knows that their color and power to change colors comes from rainbow, she then tells them the history as she gives them a tour. Ice King comes into rainbow kingdom via the open portal, planning to kidnap the princess and take her to his castle to convince her to marry him. He flies to the Rainbow Castle and grabs RP, she fights a bit but is frozen from neck to toe in ice then yells to her staff to find Marceline and tell her what happened. Ice King leaves the portal with her and the rainbow kingdom and people black and white. Finn and Jake are wondering what happened, and Marceline doesn't like what she thinks it is. One of the staff runs up to them and says that the princess was kidnapped and taken through the portal. Marceline says that they have a limited amount of time before the portal closes. Finn asks how much, and Marceline says two hours and was going to continue but is then interrupted by Finn freaking out and tells Jake they need to hurry and find her. Jake says to hop on his back and they go through the portal. They see the land of Ooo was also black and white. Marceline follows behind to say she wasn't finished and that they two hours in the Rainbow Kingdom but a day in the land of Ooo. Jake and Finn sigh in relief, and Marceline says that five hours have passed in Ooo and they have 19 hours left. She floats higher in the sky and yells to them that while the land is colorless, the one mile radius around rainbow princess is colored so they have to find her by sight. They head to the ice kingdom to start searching, but notice that it's still black and white, so RP couldn't have been there. They search for RP; Jake and Finn by land and Marceline by sky but 14 hours go by and they start to loss hope until Finn recalls the Ice King's underground chamber. They go back to the Ice kingdom and go inside the castle. They notice the entire floor has color, RP must be with Ice King in his underground chamber. They bust in on them, and Finn yells to ice king to let the princess go, but Ice king gets angry and tells Finn that he will not ruin the connection the princess and Ice King are getting. Rainbow Princess yells that they are not having a connection and pleas to her friends to free her. Marceline whispers to Jake that he needs to help Finn distract the ice king, get the key, and then give it to her. Jake nods and whispers to Finn the same thing that Marceline told him, Finn says got it and fights with the ice king while Jake stretches his arm to grab the key and hands it to Marceline. She opens rainbow princess's cell and lets her out. The princess watches Finn and Jake fight the ice king and says to Marceline that she finds Finn cute (in a little boy way) and heroic. Marceline just shrugs and moves on. Finn and Jake tie up the ice king and Finn asks how he knew about rainbow princess in the first place. Ice king answers that he saw a hologram of her, that she was telling her staff to build a crystal chamber near the ice kingdom. This explanation causes a silence as everyone turns to RP. The princess calmly says that the chamber acts as a signal booster and helps to make the colors look more vibrant and that she has many of them in secret locations around Ooo. Marceline looks to the sky and yells in a worried way that they only have an hour let till the portal closes. Jake and Finn freak out and have RP get on Jake's back with Finn. She smiles as she rides with them back to the portal and thanks Finn for rescuing her and hugs him afterwards, making him blush a little. They get to the portal just barely too late and it closes on them. They all get depressed except RP and Finn says how sorry he was to not get her to her kingdom in time. She smiles and laughs a little then saying "don't worry about". They get confused then the princess asks Marceline if she still has that rainbow crystal she gave to her some time ago. Marceline reaches into her pocket to pull out her key chain and look at the crystal then suddenly realizes that this crystal is a copy of the one in RP's kingdom and can transport them back. The princess nods and Marceline spins a circle in the air and opens a portal. The princess squeezes her right hand to make another rainbow crystal and gives it to Finn. She says to him that he can visit her any time he wants, then she kisses him on the cheek and says "Thank you. You're a very noble boy, Finn the Human". He blushes then Marceline asks "what do you think about her?" and Finn answers "she's pretty math".