He looked back at the screen. The video had paused itself. In the reflection of the black monitor, he saw his own bedroom door slowly swinging open, mimicking the frame-by-frame movement of the footage. The sub-harmonic hum was no longer coming from the computer—it was vibrating in his chest.

When he clicked play, the screen didn't show a person. Instead, it was a fixed shot of a hallway in an empty hospital, the fluorescent lights flickering in a rhythmic, heartbeat-like pattern. There was no sound except for a low, sub-harmonic hum that made the glass on his desk vibrate.

Elias leaned in, his breath fogging the monitor. Just as the door in the video began to creak open, a soft thud echoed from behind him. He froze. The sound hadn't come from his speakers. It had come from his own hallway.