Psychologist Lin Yun receives the strangest case of his career: after responding with "Is anyone there?" to a late-night campus broadcast, his patient develops bruises around his throat as if strangled by an invisible rope, and loses the ability to speak. Whenever he tries to open his mouth, he hears the cold sound of dripping water beside his ear, along with a voice coming from the darkness...
"Why... did... you... answer?"
