Maria (Dakota Blu Richards Dakota Blue Richards), whose father is heavily in debt, is left with a thick ancient book, the History of the Moon flat, which records the fairy tales of the Moon Princess and the White Horse. Thirteen-year-old Maria becomes an orphan and comes to Yueliangping Manor to turn to her uncle Benjamin (played by Ian Gruffudd Ioan Gruffudd). However, shortly after staying in the castle, Maria found strange things coming one after another: her things were always misplaced everywhere, the piano in the house would be played automatically, and there was even the shadow of a white horse hanging outside at night. However, my uncle refused to reveal a word of these questions. Maria had to secretly read the ancient book that had been hidden by her uncle, and finally learned that there was a long mysterious past and hatred on the moon flat. It turned out that the whole valley had been shrouded by the curse of the moon princess for a hundred years. We can only wait for a person with a pure heart to appear. This film is adapted from the classic novel "the Princess of the Moon in the Castle" by Elizabeth Gucci, a British children's writer.