One day, Duncan is happily coloring with his crayons when a stack of postcards arrives in the mail from his former crayons, each of which has run away or been left behind, and all of which want to come home.
"The crayons are getting ready to go back to school, and each crayon has a subject they're looking forward to the most. They're also ready to meet new friends ... and let loose during their very favorite time of day: art class"--
When a shy unicorn's colors start to fade away, a group of spunky crayons band together to help their new friend get back his colors and gain self-confidence in the process.
When best friends Sun and Clouds clash and refuse to share the sky, Earth's colors are threatened until one little box of crayons creates a huge rainbow that reconciles the friends and brings color back to Earth.