This is not the Branch Davidians, the Manson Family, or Jonestown… but it might as well be. This particular commune is called The Haven, and may not be breaking news at the moment. But it is stealing Cara from her best friend, Mailee, and no matter how much the teen attempts to keep Cara, her friend recedes further into the clenching grip of a man named Firehorse. Mailee is immune to his appeal; Firehorse scares her and she wants nothing more than to rid herself and her friend of him.

This journey into darkness all beginswith a chance meeting at the local mall. The girls meet Avalon and her mother, Alexa, who invite them to visit their home in the woods. Cara seems interested, not least of which is due to Avalon's age, similar to that of Cara's sister, Harper, at the time of her death.  Sadness radiates from Cara's very core any time that she thinks of Harper or visits her sibling's old bedroom. 

Mailee's boyfriend, Gavin, shows a similar distaste for The Haven and Firehorse's creepy ways. Firehorse posts a website chock full of his ideologies, including his dislike for technology and contemporary ways. He wants and demands that his followers fully and completely buy into every idea that he espouses, and he does not take to criticism or disagreement well.

Mailee is not exactly an outdoorsy kind of girl, and she deeply fears for Cara's safety. Every time Mailee tries to awaken her friend from the Firehorse's aura, Cara explains why she is even more committed to living in the woods with her new friends.

Girl In a Bad Place by Kaitlin Ward, 2017

This seems to be a well-researched book on cults and how they operate and lure followers. 

Books on cults

Kaitlin Ward's website