Cai Xiaoai, a "Truman Girl" who suffers from a rare disease, meets Gu Eun-jo, a girl with a tragic but strong life experience, Song Can-he, a gentle and caring senior, and Lu Haoyu, a quirky man. The four of them continue to grow while experiencing a series of difficulties. At the critical moment, they help Cai Xiaoai expose the lies behind the saboteurs, and with the efforts of everyone, Cai Xiaoai regains her health. In the end, the four of them shine for their own lives.