While investigating a case involving North Korean criminals, national agent Le Li goes undercover at an entertainment venue in Linxia under the alias Xiao Ye. There she meets Ning Sishu, a North Korean prosecutor who has infiltrated Linxia to investigate South Korean officials. Ning Sishu is of mixed Chinese and Korean heritage. He had already crossed paths with Le Li on a plane, where she was assigned to protect him temporarily until he boarded his flight. After facing life-or-death dangers together several times, Ning Sishu, with his simple and gentle nature, makes no secret of his admiration for Le Li, who is outwardly soft but inwardly strong and full of character. But Le Li remains elusive and distant, refusing to accept his feelings.
