Chapter One: The Empty Car

At 12:07 a.m., the last train on Linchuan Metro Line 2 pulled away from Baiyu Station. Cheng Du stood beside the doors of the third car and watched darkness swallow the platform. Baiyu had been sealed three years ago after severe water seepage, yet tonight the signal room had repeatedly reported someone pressing its emergency stop button. Cheng had gone down with his testing case. He found nothing but wet footprints emerging from the tunnel and ending at the yellow line, as if someone had stood there waiting for a train. As the doors closed, he distinctly heard someone running behind him. The security feed showed an empty platform.