The short was announced on September 2, 2014, as part of The Story of Frozen: Making a Disney Animated Classic. It featured a new and original song called "Making Today A Perfect Day" written by Kristen Anderson-Lopez and Robert Lopez, and premiered in theaters on March 13, 2015, in front of Disney's live-action film Cinderella.
Queen Elsa is excited because today is Anna's birthday and intends to make sure her sister's special day is perfect. Using her ice powers, she creates a special ice decoration on the top of Anna's birthday cake: figures of Anna and Elsa ice-skating happily together. Kristoff made a banner that he hung up across the castle courtyard which reads "Happy Birthday Anna". Elsa and Kristoff spent all morning preparing everything and now time was running out. Before dashing off to wake up Anna, Elsa leaves Kristoff in charge of looking after everything until the guest of honor arrives.
Elsa tiptoes into Anna's room and gently nudges her sister, who is still asleep. Anna struggles to wake up but after being told about the day Elsa has planned for them, she immediately jumps out of bed. When Elsa sneezes, neither of the sisters notice that two tiny snowmen pop into the air, drop to the floor and scamper away. Starting off the day, Elsa uses her magic to create sparkly new dresses for each of them before heading out on a mystery tour which involves following a long string that Elsa had wound through the castle, leading Anna to different gifts. Inside a suit of armor, Anna finds a bracelet. Inside an armoire, she finds an Olaf cuckoo clock. And on a balcony, there's a bouquet of sunflowers. Elsa sneezes again and more little snowmen pop into the air and tumble to the ground, but still the girls don't notice. The snowmen scurry into the courtyard where Olaf finds them and is thrilled to see them. Anna and Elsa follow the string all over Arendelle. Along the way, Anna discovers more presents: a family portrait, silk stockings, even a fishing pole. All the while, Elsa continues to sneeze and each time she does, more little snowmen appear and still the girls don't spot any of them. Anna is having a wonderful time but is concerned for Elsa's health. She feels she should go home and rest but Elsa declines. She leads Anna to Oaken's shop, where she presents her with one of Oaken's beautiful heavy cloaks. Then noticing her sneezing, Oaken presents them with a bottle of medicine which Anna accepts gratefully, knowing they may need it. Next, Elsa takes Anna to the center of the village, where a children's choir sings for Anna.
Back at the courtyard, Kristoff, Sven and Olaf try to keep things under control as more tiny snowmen run in, causing a lot of chaos and trouble for them. When Kristoff spots several little snowmen climbing up to the cake, he grabs Olaf's head like a bowling ball and takes aim. Olaf's head rolls into the snowmen, knocking them away from the cake. Suddenly, the little snowmen knock down Kristoff's banner. Olaf manages to rehang the letters, but since he cannot read, they spell "Dry Banana Hippy Hat".
Meanwhile, Elsa leads Anna to their last stop, where at the top of the clock tower was her last gift. Anna's arms are now overloaded with presents and Elsa's cold is getting worse. Anna insists that Elsa needs to rest, but she doesn't listen. Already she is feeling feverish as she climbs the stairs to the top of the tower till finally she loses her balance. Anna drops her gifts and rushes to catch her. She notices Elsa is burning up with a fever and needs to get into bed, which Elsa finally agrees to. As Anna escorts her home, Elsa feels she ruined her perfect birthday but Anna tells her she hasn't. Then as they enter the castle gates, Anna is surprised by Kristoff, Sven, Olaf and the hundreds of little snowmen who present her with her birthday cake and a special birthday song. Caught up in the excitement of the song, Kristoff sings loudest of all and bursts out "I love you, baby!", becoming very embarrassed while a touched Anna grins at him happily. Though tired, Elsa insists on blowing the Birthday Horn, and sneezes into it, launching a gigantic snowball all the way to the Southern Isles, where it hits Hans as he is shoveling manure at the royal stables.
Afterwards, Anna helps Elsa into bed and thanks her for a great birthday and giving her the best present she could ever have: Elsa letting her take care of her. High on the North Mountain where stands the ice palace, Marshmallow is visited by Kristoff, Sven and Olaf who present to him a parade of the little snowmen who would now be living with him.