Underachiever Chen Yan accidentally rewinds back to three days before the college entrance examination, triggering a mysterious rewind mechanism. On a rainy night, he encounters the campus belle Li Yanxi, who is plunged into the grief of losing her mother and harboring suicidal thoughts. While trying every possible way to gently guide and hold onto the desperate girl, he prepares for the college entrance examination, deals with daily campus life and trivial family matters, and tries his best to rewrite the tragic destiny. Accompanying and healing each other, in the tense finale of senior year, the two together seek the meaning of living and face the scars of youth and future choices.