A widowed old professor (Min-seop) with one more semester to go until his retirement, leaves for his son’s house in America during the summer. He asks Young-jo, a graduate school student he is sponsoring, to organize his personal library and asks Yun-soo, another close young man working at the flower shop to take care of the orchids his wife had cherished all her life. At the professor’s house in the morning Young-jo finishes organizing the books, and in the afternoon, Yun-soo takes care of the orchids, yet the two of them misunderstand each other even without meeting. While they work on their own, they discover the traces of the professor and his deceased wife. At around the time they realize the invisible love the couple has bestowed upon them, the professor passes away and the summer of Young-jo and Yun-soo comes to an end.