The Sun and the Clouds are best friends. Together they keep the world warm, the gardens growing, and the sky full of beautiful rainbows. But one day they get into a fight and refuse to be in the sky together. And that means there are no longer any rainbows. Without rainbows, the colors start disappearing until Earth was left with no color ... except for one little forgotten box of crayons in one little school desk.

Determined to save the rainbows and fix the Sun and Clouds' friendship, the crayons draw rainbows all over town. Their attempts go unnoticed. Soon they realize that they're going to have to do something big to get the attention of the former friends. So, the crayons create the biggest rainbow they can and hope it's enough to bring color back to the world.