The hair on the back of your neck stands up, with the telltale knowledge of eyes falling upon your silhouette. Your eyes dart around, your head swivels. Then the air stills for a moment, as though the world is holding its breath. A flicker of light flits across your vision. Adrenaline fires through your senses, amplifying them, ready to react. But then… silence. The world returns to life, your heart pounding in your chest the only proof that the moment even happened.