Due to the hospital bills for her suddenly ill daughter, Sun-mi, single mom Jo E-Sun quits her job as a web designer and starts working in insurance sales. She decides to attend the annual reunion of her elementary school for the first time, but as long-buried memories resurface, the atmosphere of the reunion intensifies. The reason she was reluctant to attend the reunion is revealed, and as she talks to her classmates, who have lived different lives, she begins to reflect on her own life. However, the appearance of a former classmate who was bullied shifts the mood. As the bullied classmate becomes intoxicated, the situation escalates, spiraling out of control.