In the not-so distant future, researchers at a deep-sea laboratory have finally invented a time machine. Head researcher Woo-seok is promised funding from a mega-corporation if he completes a test flight. He and Young-eun carry out the mission and travel to 11 A.M. the next day, only to find the base on the verge of collapse. All the researchers are gone and someone is out to kill them.

An elderly woman who files endless complaints with the local office to right the wrongs around her forms an unlikely friendship with a junior civil servant when she begins learning English from him.

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.