Watch the Terrifying First Trailer for HBO Doc Beware the Slenderman

For all of its benefits, the internet can be a dangerous place. That’s hardly been more true than it was after the attempted murder of a 12-year-old girl in Waukesha, Wis., by two of her schoolmates and close friends. The pair claimed to have lured the girl into the woods and stabbed her 19 times because of the Slenderman, a monster whose urban legend has spread across the internet.

Now, HBO has unveiled its first trailer for Beware the Slenderman, a documentary that takes a look at the aftermath of the near-murder and its significance. The documentary also unpacks the myths surrounding the Slenderman, who is supposed to be between 6 and 14 feet tall, is dressed in a well-tailored suit and has no face.

The two children who committed the crime claim that the Slenderman threatened to kill their families unless they offered a classmate. The fascinating material will certainly make for a gripping documentary, and may also help us make sense of the role the internet plays in distorting the world we live in.