My Best Friend's Exorcism - Grady Hendrix

The year is 1988. High school sophomores Abby and Gretchen have been best friends since fourth grade. But after an evening of skinny-dipping goes disastrously wrong, Gretchen begins to act different.

She s moody. She s irritable. And bizarre incidents keep happening whenever she s nearby.

Abby s investigation leads her to some startling discoveries and by the time their story reaches its terrifying conclusion, the fate of Abby and Gretchen will be determined by a single question: Is their friendship powerful enough to beat the devil?