Thirty-four years ago, nine children vanished without a trace from the Beicheng Welfare Home. Shen Li was the only one who was “sent back.” Now a criminal investigator, he spots a little girl in the last row of the final bus of the night, though she never appeared on the surveillance footage boarding it. She carries nine old coins and asks for “the one who was sent back.” As the investigation deepens, a charity fund, a hospital, logistics companies, and public services all come to light. Someone doesn’t need to take a life, only erase a name from society’s records. Someone else truly saves people, yet also decides whether they get to go home. The Nine Seats always remain occupied. When one seat is left empty, another fills it. As the evidence gradually points to the First Seat, Shen Li realizes that the real endgame is not just catching the mastermind. He must answer one question: to save someone, will he take that empty seat?
