The Captain Rainbow of the title is the alter ego of Nick, a typical geeky guy with a penchant for loud, flower-themed clothing. As the eponymous captain, he's a super-studly hero with a bunch of crazy fighting moves and a magic yo-yo to finish the bad guys off with, but his popularity with the kids just isn't there -- in fact, the ratings for his TV show are just about in the dumps. So Nick takes a trip to Mimin Island, a fabled land where it's said your wishes can come true -- but thanks to an unexpected turn of events, it's actually Captain Rainbow who has to help out all the island's inhabitants with their own wishes.