Twenty-year-old Hannah, living in LA, discovers that her twin sister, Hana, whom she had never known about, resides in Korea while searching for a donor for her mother, Sun-ok, who needs a liver transplant. Hannah travels to Korea to ask Hana for a liver transplant, and they spend several days together, building a bond. During this process, Hannah learns that she and Hana were born from a surrogate named Seon-jeong. Eventually, the four of them begin to reveal their truths to each other in one place.