Beware the Slenderman Trailer (2016)
Trailer for the documentary Beware the Slenderman, which will premiere on HBO in 2017. Docu tells the true story of 12-year olds Morgan Geyser and Anissa Weier, who lured their best friend into the woods, stabbed her 19 times, then confessed they did it to appease a tall and faceless man known online as Slenderman.