Thirty-four years ago, nine children from Beicheng Welfare Institute disappeared mysteriously, and only Shen Li was "released". Now a criminal police officer, he saw a little girl in the last row of the last bus who had never gotten on the bus from the surveillance camera. The girl took nine old coins and looked for "the person who was released" by name. As the investigation deepens, charitable funds, hospitals, logistics and public systems have come to the surface one after another: some people do not need to take lives, but only need to make a name disappear from social records; some people sincerely save people, and they are also deciding whether others can go home. The nine seats always maintain nine positions. If one seat is empty, it will be filled. When all the evidence gradually pointed to the first seat, Shen Li discovered that the real outcome was not only to catch the person behind the scenes, but to answer a question - in order to save people, would he sit on the empty chair?
