In this enthralling book, Ben Alderson explores one of the most curious experiences known to humankind: the universal, disturbing sense that someone or something is there when we are alone - the feeling of an unseen presence. When and why do presences emerge? What does this feeling mean, and where does it come from? And how can we even begin to understand a phenomenon that can be transformative for those who experience it, and yet so hard to put into words? The answers to these questions lie in this fascinating exploration through cutting-edge research in contemporary psychology, psychiatry, neuroscience, and philosophy