A school field trip to Henderland, a theme park built around a fairy tale, goes sideways when Shinnosuke wanders off from his classmates and winds the key of a dancing doll in the park's restricted section. The doll, Toppema Mappet, tells him the fairy tale is real: the evil twins Makao and Joma have a princess under a spell, and only a living person can use the magic cards that beat their dark magic. Shinnosuke agrees to help once he finds out the twins have swapped his parents for enchanted puppets.