My Best Friend's Exorcism.

The year is 1988. Abby and Gretchen have been best friends since fourth grade. After an evening of skinny-dipping goes disastrously wrong, Gretchen begins to act…different, which leads Abby to suspect her best friend may be possessed by a demon. With help from some unlikely allies, Abby embarks on a quest to save Gretchen. But is their friendship powerful enough to beat the devil?