There is chaos in Rainbowland. For years, the world has been held under the wicked darkness of the King of Shadows. All things colorful, cheery and brite are banished; the flowers don't bloom, the sun doesn't shine, the rainbows don't... bow.
The Color Kids1, keepers of the star sprinkles and protectors of color-mining sprites, have heard that a revolution is coming. The prophecy tells of a savior, who will liberate them from the gloom and bring color back to their world. Their hope is dwindling, the future looks grim. Will emancipation ever be theirs?
Her name is Wisp. She's young, cheerful, and outraged by what's happening in the distant Rainbowland. She embarks on a quest to bring color back to the land, while defeating the eeeeevil King of Shadows and his two goons, Murky and Lurky. Along the way she meets Twink, a lovable white sprite and Starlite, a beautiful (and pompous) horse with a rainbow mane. Together they find the holy grail--I mean the color belt and sphere of light, liberate the seven Color Kids, and restore peace, harmony, and briteness to the land. Wisp was renamed Rainbow Brite, and given the task of defending the Color Castle and all of Rainbowland from oppression and the forces of darkness.
Thus, the Rainbow Brite franchise was born.2 The year was 1985 when Rainbow Brite books, shows, toys, and games flooded the market like so many cartoons since. Plush, squeaking sprites were sold at Taco Bell, Rainbow Brite and the Star Stealer hit the silver screen, and children all over the world found new joy in "prismatism."
1The Color Kids are (in Roy G. Biv): Red Butler, Lala Orange, Canary Yellow, Patty O'Greene, Buddy Blue, Indigo and Shy Violet.
2Rainbow Brite was originally created by Hallmark to push cheerful greeting cards in '83. In 1985, she started her career as a toon.
Some information provided by http://www.80scartoons.net/toons/rainbow.html