A little girl and her brother play with her imaginary gold-horned unicorn that can float on water, fly, and turn herself into a fairy princess.

The magic tree house carries Jack and Annie to New York City in 1938 on a mission to rescue the last unicorn. The city is in the grip of a terrible snowstorm. To stop the blizzard, Jack and Annie must save the unicorn made famous in the Cloister's medieval tapestries. But will that be enough to help a city that faces so many troubles?

Despite disagreements on the wisdom of the adventure, Rainbow Tinseltail and the other unicorns set out for Snowbelle Mountain to find out if Yetis are real--and when they get caught in a blizzard and take shelter in a cave they find the answer to their quest.

Merbaby Flo was born with only one fin, unable to swim--so Bo and the other unicorns set out for the Shiny Sea to find the Golden Fish and ask Goldie to use his magic to help baby Flo.

In order to earn their Bravery Patches, Bo and the other unicorns of Sparklegrove Forest have to camp out in the forest for three nights; but the night is full of frightening noises, and when a misunderstanding offends some pixies, the unicorns resolve to face their fears and confront the "monsters" who are stealing the pixies' houses.

Nimbus, a lonely pegasus, searches for a fallen star to wish for a friend and meets a unicorn named Kelp along the way.