Beware the Slenderman (HBO)

It was a local story that horrified the nation: two 12-year-old girls lured a friend into the Waukesha woods, where they proceeded to stab her 19 times in an effort to appease a faceless mythical entity known online as 'Slenderman.' This sobering documentary delves deep into the story and examines how an Internet urban myth could take root in impressionable young minds.