This movie's title sounds kind of misleading then. What is it actually about?
In a way, Beware the Slenderman has less to do with its titular character and more to do with the psychological and legal aspects of the Waukesha incident. Since Brodsky couldn't interview the Leutners, she spent a lot of time with Morgan and Anissa's families, humanizing their end of the story in a way that's insightful and sensitive. The movie doesn't just touch on what happened, but also why, and, in a cautionary sense, what the stabbing could mean for other families. In fact, Brodsky hints at big moral questions about brain development, internet access, and whether children should be held accountable for adult crimes.
What should I know to better understand that aspect of the movie?
A few things: