The movie "Butterfly on Shoulder" is adapted from Fu Yupeng's online article "Do You Have a Butterfly on Your Shoulder?" The story takes place on an island threatened by a deadly infectious disease. The famous biologist Yan Guo (played by Chen Kun) focuses on research, hoping to find a cure for the disease, but he is attacked by the disease and is dying. His fiancée Bao Bao (played by Jiang Yiyan) makes a contract with a mysterious creature: to become a butterfly in exchange for Yan Guo's recovery for three years. Yan Guo recovered his health but lost his lover, becoming depressed and withdrawn. Bao Bao, who turned into a butterfly, can only watch him become depressed day by day but can't do anything. Yan Guo gets the care of his neighbor Bai Lan (played by Gui Lunmei) and female reporter Yang Lin (played by Gigi Leung). Love develops between Yan Guo and Yang Lin, which makes Bao Bao full of pain. In the last year before Bao Bao can turn back to human, an epidemic breaks out on the island, and Bao Bao finds that she can find the key formula of the antidote that Yan Guo is researching. The dangerous journey makes her wings broken, but she still doesn't give up. Can the scarred Bao Bao bring the medicinal formula that Yan Guo needs and fly back to him? Will she become human again? Who will Yan Guo choose in the end?