Billy is having a lovely day on the beach with his mum when he is faced with the challenging task of saving the rainbow. Billy is shocked to learn that if rainbows don't exist anymore then baddies can take over Earth. Something unexpected happens to Billy and he is very scared, but he uses his bravery, courage, and creativity to think of new ways to save the rainbow. How will Billy save the rainbow? And will he save it in time, before the baddies take over the world?