On the first day of summer vacation, ten-year-old Banxia receives a mysterious gift from her grandmother: an old copper key and a note that reads, "Keep the key safe."
An ancient wooden door in the backyard, covered in ivy, is a perfect match for the copper key. When she opens it, she enters a fairy-tale world filled with magical creatures and strange plants.
What is the connection between this bewildering fairy-tale world and the ancient copper key?
Core theme: Open up the summer in your heart
