Tap.

The rock had come out of nowhere—a stray piece of asphalt kicked up by a semi—and punched a spiderweb crater through his rear windshield. One second he was listening to a podcast about urban legends; the next, the back of his car exploded into a constellation of cracked glass and icy wind.

Sam saw his own face, split into a thousand tiny reflections, smiling back at him from inside the car.

He pulled over, heart hammering. The damage was bad: the entire rear window was shattered but still clinging together like a fractured mirror. A single good bump, and it would rain shards all over his backseat.

Sam did what any desperate driver would do. He pulled out his phone and typed into a search forum: “Can I drive with a broken rear window?”

Tap.

Curious, he clicked.

Rule 3 was the strangest: If you hear tapping on the remaining glass, do not stop. Do not turn around. Drive until you hear three taps, then pull over immediately and get out of the car. Do not look back.