Lin You is a female high school teacher. On the morning of the first summer vacation of her first year in the profession, she had a strange dream. She dreamed that she traveled through a field of sunflowers and entered a magical room. There were three other doors inside that door. Each door was full of different people and different things. When she woke up, she felt lost, so she decided to go back to her alma mater to see the sunflower field, but she did not expect to miss the invitation from her ex.