Set in the 80s during the height of the Satanic Panic, this briskly-paced horror story focuses on the intense friendship between two high school girls: Abby and Gretchen. Abby comes from a poor family and is self-conscious about her poor complexion. Gretchen is more confident and affluent, but feels incredibly stifled by her religious, Republican parents.

Early chapters take their time, showing how the pair met and walking the reader through some key moments in their friendship. Things rapidly escalate after they, along with other friends Margaret and Glee, have a sleepover at Margaret's cottage. After some skinny-dipping, the teens have a disappointing experiment with LSD, after which Gretchen disappears overnight. Abby finds her the next morning naked and alone in the woods, clearly agitated but with little memory of the previous night's events.

After the sleepover, Abby notices marked changes in her friend. She complains of phantom groping, refuses to bathe or change her clothes, and grows distant and uncommunicative. Despite being rebuffed by her friend and ignored or treated with hostile skepticism by adult authority figures, Abby embarks on a desperate and dangerous mission to save her best friend.

Much like the author's previous novel Horrorstör, there are touches of humor throughout the book, including graphic inserts of newspaper clippings and advertisements. Like the humor, the 80s setting is used to good effect. Sensational journalism had put Satanic conspiracies and demon worship at the forefront of Americans' minds, making that decade a natural home for this novel. Hendrix indulges in some references to the pop culture of the era, including naming all the chapters after pop songs, but wisely doesn't go too overboard with the nostalgia-baiting.

Despite some of the lighter touches, this becomes a nicely creepy story when Gretchen's possession is in full swing. The book never really erupts into a bloodbath, much of the demonic influence is more subtle and manipulative, but Abby's isolation and her fear for her best friend are communicated very effectively.

There's a great risk of "love conquers all" plots becoming cheesy or corny, but this is a good story about the power of friendship. It acknowledges the ups and downs and occasional limits of friendships, but also the strength and staying power of some rare relationships. While the titular exorcism was well done and much more unique than seen in these kind of stories, it was the denouement that I found most satisfying.

Highly recommended for horror fans (especially if you can remember the 80s) and maybe even those who read spooky YA books. And go hug a friend.