On a rainy summer day, a girl named Kim Tae-hee (played by Lee Eun-joo) walked under the umbrella of a boy named Seo In-woo (played by Lee Byung-hun) to take shelter from the rain, and the boy fell in love with her at first sight. The relationship between the two gradually warmed up in college. On rainy nights, the two quarreled and reconciled, and their feelings were so strong that they could not be dissolved. The night before Renyou went to the military service, he did not wait for Tae-hee who promised to see him off, and thus missed the chance to meet him. 17 years later, Seo In-woo already has a happy family, and his wife and little daughter make his life calm and peaceful. He teaches in a boys' school and finds that the actions and behaviors of a 17-year-old boy in his class are strikingly similar to those of Tae-hee back then, which evokes his memories that he has buried for many years, and he realizes that he has never been able to forget them. The boy's heart was also moved by Renyou's feelings. He even broke up with his girlfriend. Where is Tae-hee? After the mystery of 17 years ago was solved, it was an extreme love of life and death.