Black Box Echo

After the collapse of the North No. 3 Mining area, Liang Yuan, the only survivor, brought back a photo from underground. In the photo, a black cube stands deep in the rock formation. No one knows what it is, and no one knows why it appears 720 meters underground. Liang Yuan left one last warning before his death: Don't let Lin Zhou hear it. Ten years ago, fourteen children from Qingshan Welfare Home disappeared overnight, and Lin Zhou was the only one who was found. Ten years later, that thing called the "black box" finally waited for him.