A wealthy young man pursues a young woman of modest means, but circumstances often separate them as the years pass.

A train ride brings two unlikely souls together as Bae, a committed partner of a serious 10-year relationship, sees her world turned upside down by the charming playboy Kim. Seated together on a business trip from Seoul to Busan, the two find themselves on an adventure to remember.

Ten years ago, on a train home during the busy Spring Festival travel period, fate brings Xiaoxiao and Jianqing together. Like many young couples, they meet, fall in love, and strive to make it work, but eventually, the harsh realities of life make them drift apart. Ten years later, they run into each other again. Will they make the most of this second chance and rekindle what they once lost?