The film begins with a famous doctor, Yan Guo, becoming extremely sick during the course of his studies. To save his life, his girlfriend Baobao makes an agreement with a mysterious creature; in exchange for the health of Yan Guo, she agrees to be turned into a butterfly for three years.
Yan Guo finally recovers from his illness and wakes up. He is confused and hurt by Baobao's disappearance, and in her absence, other women begin trying to attract his attention. Meanwhile, Baobao begins living her life as a butterfly but finds that the other insects will not associate with her, finding her too human.
Soon, a dangerous and infectious disease begins spreading on the island. Both Yan Guo and Baobao try their best during this time to help those around them. When the three years have passed, will they have a happy ending?
