Elias turned around, but the room was empty. The only thing left was the sound of a new file being created on his hard drive: . He didn't want to know what was in that one.

Most people would have swiped it away. Elias, a night-shift data archivist with a habit of poking at digital bruises, tapped it.

He waited for the "jumpscare," the loud scream or the masked face to pop up. It didn't happen. Instead, the runner in the video reached out a hand—covered in a black latex glove—and tapped on the glass. Tap. Tap. Tap.

A new notification appeared: