Fionna (the gender-swapped version of Finn) puts up with the sudden courtship of Prince Gumball (the gender-swapped version of Princess Bubblegum) while taking advice from her partner Cake (the gender-swapped version of Jake) in dealing with guys.
The episode opens with alternate versions of Finn and Jake, using gender swapped characters. Fionna and Cake are helping Prince Gumball decorate for the Biennial Gumball Ball when Prince Gumball asks Fionna if she would like to go to it tonight with him "as pals." Their conversation is interrupted when Cake's tail frizzes up, sensing incoming danger. Fionna rushes to the balcony and sees the Ice Queen coming down from dark clouds to kidnap Prince Gumball. She breaks into the castle, forms a slush beast around herself and goes after Gumball. Cake turns into a morning star that Fionna uses to smash the slush monster, with Ice Queen and Gumball inside. The room fills with snow, and Prince Gumball appears unharmed, but Ice Queen has mysteriously vanished. Prince Gumball then asks Fionna to "go out" with him, and Cake agrees for her to meet him again in an hour at the Castle Gardens.
At the Tree Fort, Fionna and Cake argue over whether or not Gumball asked Fionna on a date. Cake insists that he did, and decides to come along to help Fionna, taking her dulcimer with her as a "conversation starter" (the alternate instrument to Jake's Viola, apparently). Fionna reluctantly agrees to this, and they go meet Prince Gumball at the Castle Gardens. Prince Gumball is joined by Lord Monochromicorn. Prince Gumball gives Cake a satchel of catnip that Lord Monochromicorn picked himself, and gives Fionna a bouquet of posies with a retractable crystal sword inside it. Fionna is much more excited by the sword than the flowers.
The group rides off - Fionna riding on Cake's back, and Prince Gumball on Lord Monochromicorn. Cake urges Fionna in an undertone to tell the Prince that he's "hot." Fionna does not like the idea, and Cake insists that "guys like to hear that they're hot!" Prince Gumball interrupts to challenge Fionna to a race to Marshmallowy Mweadows. The group races there, and Fionna and Prince Gumball jump off their friends and into the flowers. Suddenly Prince Gumball dives under the flowers and disappears. Panicking, Fionna dives after him and pulls him out. Gumball explains he saw a pearl pygmy skull in the flowers that reminded him of Fionna's sparkling eyes. Fionna giggles, her eyes growing wide and glimmering like Gumball's. Later the group flies off on Lord Monochromicorn, and Prince Gumball sings about Fionna while Cake plays along on her dulcimer. The flight ends when Cake and Lord Monochromicorn drop Fionna and Prince Gumball off in a grassy field, leaving them alone together. After lying on the ground talking for a while, Prince Gumball asks Fionna to come to the ball with him as his girlfriend.
Fionna rushes back to the Tree Fort and excitedly yells to Cake that she is now going to the ball as Gumball's girlfriend. After Cake dresses her up in a fancy gown, Fionna asks how she is supposed to fit weapons in her purse. Cake says she does not need weapons at a ball, but Fionna takes with her the retractable crystal sword that Prince Gumball gave her anyway. When Fionna and Cake get to the ball, Marshall Lee floats by and gives Fionna the "horns" sign. Prince Gumball is seen talking to the female Cinnamon Bun, then he comes to Fionna and takes her to his room, decorated with candles and rose petals, and locks the door. She becomes flustered and, blushing, backs away when he begins to take his shirt off. A drop of water lands on her shoulder, she looks up to see the real Prince Gumball trapped inside a giant icicle on the ceiling. The fake prince is revealed to be Ice Queen, now taking off her disguise.
Enraged by the deception, Fionna takes out the crystal sword to fight, but the sword is another one of Ice Queen's tricks and turns into a ball of ice around Fionna's hands. Cake hears noises from downstairs and senses Fionna is in trouble. Undaunted, Fionna uses the ice to beat Ice Queen over the head. Ice Queen pushes her off in burst of snow, which allows Fionna to get close to enough to break Prince Gumball free. Ice Queen gets knocked down by the broken icicle pieces just before Cake bursts into the room. Seeing Gumball standing next to Fionna in her torn dress, Cake jumps to the wrong conclusion and lunges at the prince. Fionna stops Cake from hurting Gumball and tells her it was the Ice Queen all along.
Just then Ice Queen recovers and blasts Cake away from Fionna with a torrent of icicles. Fionna knocks her magic tiara off, squelching her powers, and then punches her for "yanking her heart-guts." Cake then uses the tiara's power to bury the Ice Queen in snow. Fionna swats the tiara off Cake's head, saying, "you'll catch her crazy!" The real Prince Gumball is impressed by Fionna and asks her on a date, but she quickly turns him down. Fionna decides she does not need a boyfriend because she knows who she is and that she is not interested at the moment, but adds that she would give anything to date the Ice King. Cake agrees, saying "Ice King is the real deal!" and Lord Monochromicorn appears and agrees too by tapping his front hoof in code. As she praises the Ice King, Fionna's voice suddenly becomes the Ice King's as the scene changes to the real Ice King's throne room. He is lounging in an armchair and reading a fan fiction he wrote to Finn and Jake, whose bodies are trapped in ice. Ice King closes the book, which has a picture of Fionna kissing Ice King, and asks. "So, what did you think of the fan fiction I wrote about you guys?"
Finn, who is the only one with his head not buried in ice, hesitates to respond. Ice King raises his hand with ice power threateningly and yells, "Tell me you thought it was good!" Finn hurriedly placates the Ice King by praising the book.