After Seon-yoo's father committed suicide leaving behind a large sum of debt for them, Mother and 12-year-old Seon-yoo move to a new place to have new start.
Celebrity guests are split into two teams to compete in various contests. One guest, known only to himself, is designated the "X-Man", and does his best to cause his team to lose the contests. At the end, all guests try to determine the X-Man's identity.