An Jing is a senior girl living in the small town of Songxi. During the process of independently writing a school novel entitled "Goodbye, Seventeen", she takes on the roles of An Na, An Qi, and An Jing, the protagonists of three separate stories. She travels through different spaces and times and meets different classmates, including the timid Straight-A-Student Han Yun, the warm senior Chu Yu, and the twin brothers Cheng Haoxuan and Cheng Haoyu, who have very different personalities.