My Best Friend's Exorcism by Grady Hendrix (2016)

In 1988, Abby and Gretchen are in high school and are best friends. After a experiment with LSD after which Gretchen goes missing for an evening, Gretchen comes back and seems very different and very wrong. Abby tries to figure out what is wrong with her friend, and tries to get help from family, friends and other grownups, to no avail. 

As the dust jacket says, "Is their friendship powerful enough to beat the devil?" Filled with pop culture references that will delight readers of a certain age (my age, btw), this is also a great horror novel and a great novel about friendship. It's an unexpected combination that works beautifully. 

Surprisingly insightful into the minds of teenage girls and all the trials and tribulations of friendship and of being a teen. It also has a yearbook design motif (probably used since Hendrix's Horrorstor used the IKEA catalog so effectively), which is a bit superfluous in this novel. Nonetheless, Hendrix powerfully captures just how powerless you are when you're a teen.

I adored this:
"Abby Rivers and Gretchen Lang were best friends, on and off, for seventy-five years, and there aren't many people who can say that. They weren't perfect. They didn't always get along. They screwed up. They acted like assholes. They fought, they fell out, they patched things up, they drove each other crazy, and they didn't make it to Halley's Comet. But they tried."
Aw!