It’s the dead of night; you are fast asleep. Abruptly, you are wide awake but unable to move. Hunched over you in the shadows is an eight- or nine-foot-tall gaunt entity with spider-thin limbs, dressed in an old-style black suit, its pale encounter missing eyes, nose, ears, and mouth. You finally manage to cry out. The monstrous factor disappears as all of a sudden as it appeared.

You just had a terrifying encounter using the Slenderman.

Who-or what-is the Slenderman? His lifetime began on the Internet, but he didn’t stay on the web. The Slenderman may be a tulpa, a thought-form that may stride out of our darkest imaginations and into truth if enough people have confidence in it. In May 2014, two young Milwaukee girls nearly killed a friend in the name of the Slenderman. Maybe, like the huge Skynet system in the Terminator movies, the Internet is turning against us-and attacking us with digital equivalents of our own online nightmares.

The Slenderman has become more active. For the very first time, this reserve reveals the entire and fear-filled saga.