Boo Kwai, a very naughty boy, accidentally arrives in a parallel universe thanks to one of his inventions.

Like all primary school students, Ma Xiaole always feels that he has too much homework to do and too little time to play. In order to urge Ma Xiaole to study, his father, who is fond of inventions, makes a smart toy called "Big Head", which follows him around all day long and annoys him to no end. By chance, Ma Xiaole meets the elf Little Yellow Riding Hood, and soon the two of them, who are also simple and kind, become friends. Little Yellow Riding Hood thinks that Ma Xiaolei should enjoy a carefree and happy childhood instead of being overwhelmed by homework every day, so he and Big Head start an even battle. Little Yellow Riding Hood is defeated by Big Head and is about to lose. At this juncture, Little Yellow Riding Hood takes Ma Xiaole into a time tunnel and travels back in time!