Sam pressed his forehead against the cold window of the last subway car, watching the flickering tunnel lights. Suddenly, a figure emerged alongside the train, sprinting at an unnatural speed, arms swinging rigidly. Panic surged as Sam's breath quickened, the distinct echo of his heartbeat drowning out the train's rumble. He squinted, trying to catch another glimpse, but the figure leaned closer, its face impossibly still. Just as the train entered a dark stretch, a hand pressed against the glass, leaving a chilling smear behind.