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?