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.
The film mainly follows the famous 1597 Battle of Myeongryang during the Japanese invasion of Korea (1592-1598), where the iconic Joseon admiral Yi Sun-sin managed to destroy a total of 133 Japanese warships with only 13 ships remaining in his command. The battle, which took place in the Myeongryang Strait off the southwest coast of the Korean Peninsula, is considered one of the greatest victories of Yi.