After losing her husband, Seo Eunhye cherishes her student Choi Jungwoo as if he were her own son.
Time passes, and the middle-schooler Jungwoo grows into a university student. That summer, he comes back to find Eunhye again.

“I want to be like a mother to you.”
“Are you crazy? You can’t have sex with your mom.”

Just as Eunhye is struggling with guilt over her relationship with Jungwoo, she reunites with her old classmate Minhyuk at a school reunion.