In the late 1960s, C’est Si Bon is the music bar where every acoustic band’s dream lies. There Geun-tae, a naïve country boy, meets the young musical prodigies Hyung-joo and Chang-sik, and forms the band named after it — the C’est Si Bon Trio. As the three young artists bicker over their music, beautiful socialite Ja-young enters the picture and becomes their muse, and a series of moving love songs come from it. Geun-tae’s pure-heartedness wins Ja-young over but when she accepts a once-in-lifetime opportunity for a shot at an acting career, they part ways. After 20 years, the untold story of their love, song, and youth at C’est Si Bon is finally brought to light.