Credit: HBO

If you’ve been following the Slenderman case, you’ll definitely want to watch this. A trailer for the “Beware The Slenderman” documentary, which is set to air on HBO, just hit the internet, and it looks creepier than ever.

For those unaware of the Slenderman attacks (also referred to as the “Slender Man” attacks), here’s a brief summary: Back in 2014, two 12-year-old girls from Waukesha, Wisconsin brutally stabbed a friend 19 times out of “sacrifice” to this fictional, faceless character, and left her out in the woods to die.

Luckily, the friend was strong and lucky enough to flag someone for help. Since, she has recovered from the vicious attack. The two girls, Morgan Geyser and Anissa Weier, were charged as adults for attempted first-degree intentional homicide, and heavily evaluated.

Credit: HBO

While the story thankfully had a good ending, with the criminals paying for their awful deed and the victim thriving after such a tragic ordeal, it’s definitely puzzling as to what convinced Weier and Geyser that Slenderman was real in the first place. Check out the trailer below.

From what we can tell, it looks like the documentary includes a lot of footage of Weier and Geyser while in custody, and also includes an interview with the victim, Payton Leutner, who describes the moment she saw the knife with one terrifying sentence.

Their trial has been ongoing — in fact, it’s been reported that psych reports that’ll show whether or not Weier and Geyser were mentally fit prior to the attack are due to be released today.

Slenderman, who is male in appearance, has a pale face and a narrow, long body. Based on stories created online, he can be found in the woods, and enjoys stalking children. Created in 2009 during a Photoshop contest through the Something Awful website, he’s been the focus of a lot of fiction and horror stories.

For Weier and Geyser, they were lead to believe that by killing a friend, they could serve as his “proxies,” and protect their family from harm.

The documentary is set to premiere on HBO on January 23rd. We seriously can’t wait to be shocked and spooked.