Beware the Slenderman: EW review

This horribly compelling documentary concerns two Wisconsin girls, Morgan Geyser and Anissa Weier, who were accused of plotting to kill a classmate, Payton "Bella" Leutner, after Geyser allegedly stabbed her 19 times on May 31, 2014. Geyser and Weier were just 12 years old at the time, but what really fueled the ensuing media interest was the pair's obsession with Slenderman, a faceless ghoul with tentacles sprouting from his back, about which countless internet stories have been written and YouTube videos created.

Director Irene Taylor Brodsky's documentary has a sensationalist title and an opening sequence that would not be out of place in a found footage horror film. It also offers a quick history of the Slenderman and plenty of evidence that Geyser and Weier were indeed influenced by this terrifying phantasm, both from the pair's parents, all of whom are interviewed in the doc, and the kids themselves. "So, there's this website called the Creepypasta Wiki," Weier is seen explaining at one point in the utterly chilling police interrogation footage, which Brodsky includes in the film. "It's full of like horror stories that are meant to purposely scare you through, like online literature and all that. And there is one of them called Slenderman. From what the Creepypasta Wiki said, he targets children most. So I was really scared knowing that Slenderman could kill my whole family in three seconds."

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So, is Slenderman the real villain here? Doubtless, some would say so, but Brodsky offers a more nuanced explanation. While Beware the Slenderman makes clear the potentially overwhelming impact of the internet on impressionable young minds, this is ultimately a story not about imaginary monsters, but the far more terrifying subject of real-life mental health issues. B+

Beware the Slenderman airs Monday, Jan. 23 at 10 p.m. ET on HBO.