In the summer of 1983, 17-year-old Lin Keming (played by Shi Zhitian) and Wang Lei (played by Cheng Yuxi) met because of an English speech contest, and the ignorant feelings sprouted. However, an accident of youth and frivolity abruptly separated the two, and also extinguished the throbbing of first love. They didn't even have time to say goodbye. The first love that had to say goodbye before it even started ended in this Bee Gees' "First of May". More than 20 years later, the 45-year-old Wang Lei (played by Jia Jingwen)'s daughter, Bai Bai (played by Cheng Yuxi), who was also 17 years old, made their lives intertwined again. The 45-year-old Lin Keming (played by Ren Xianqi) received a letter from the Internet, a letter from Wang Lei that seemed to be belated, which reminded him again of the innocent youth, the arrogance of the 17-year-old, and the lonely regret. It seems that this special age is destined to have a special meaning. The 17-year-old Bai Bai is also in an emotional confusion. Faced with the boy she likes and her best sister, she doesn't know how to choose...