See the Haunting Trailer for HBO's Slenderman Documentary

In 2014, two 12-year-old girls lured another child to the woods in Wisconsin and stabbed her 19 times. The two girls later explained that they were told to do it by the fictional character Slenderman. Now, this horror story is being made into an HBO documentary, coming to the cable network on January 23. The trailer for Beware the Slenderman can be seen below.

The documentary follows the events that took place on May 31, 2014, in Waukesha, Wisconsin. It is a haunting mixture of reality and urban legend, featuring reenactments as well as police video of the young girls being interrogated after the crime.

HBO has had a very successful run with recent documentaries like the 2015 mini-series The Jinx: The Life and Deaths of Robert Durst. Aside from the critical acclaim, each episode of the show averaged 3.2 million viewers according to CNN.

Slenderman was created in 2009 by Eric Knudsen on the Something Awful forums. There are many stories and art pieces featuring the fictional character, who is known for abducting, terrorizing, and stalking people, including children. He's been featured in many stories and even a couple video games: Slender: The Eight Pages and Slender: The Arrival.