"Secret Love Affair" tells the story of secret romance between Oh Hye-Won, a woman in her 40's, and Lee Sun-Jae, a man in his 20's. Oh Hye-Won, works as the director of planning for the Seohan Arts Foundation. She is elegant and excels at dealing with other people. Oh Hye-Won becomes involved in a love affair with Lee Sun-Jae. He is genius like pianist in his 20's.