(played by Gong Yoo), a cynical, workaholic fund manager who is emotionally distant from his young daughter,

. For her birthday, Su-an asks to visit her mother in Busan. Reluctantly, Seok-woo takes her on the high-speed train from Seoul.

The movie takes place on a train traveling from Seoul to Busan, South Korea's second-largest city. The story revolves around Seok-woo (played by Gong Yoo), a divorced father who is traveling with his daughter, Su-an (played by Kim Su-an), to visit her mother. As they board the train, they are joined by a group of passengers, including a couple, Sang-hwa (played by Ma Dong-seok) and Yeon-seok (played by Kim Eui-sung), and a high school student, Soo-jin (played by Kim Su-an).