Twins Eli and Ellie are terrified of growing up because they believe it will turn them into "dults"—boring, serious humans who've lost their sense of fun. Determined to stop this from happening, the twins team up with their friends to help the grown-ups around them rediscover the joy and creativity of childhood. Together, they embark on hilarious and heartwarming adventures to reverse their parent's "dultisms" by reminding them of the power of play.