Three teenage friends get into a fight, and one of them accidentally gets killed. The two remaining girls promise each other to keep silent. As the police get more and more suspicious, the mother of one of the girls gets into a crushing dilemma: protect her daughter or see justice done.

What starts as a poignant medical documentary about Deborah Logan's descent into Alzheimer's disease and her daughter's struggles as caregiver degenerates into a maddening portrayal of dementia at its most frightening, as hair-raising events begin to plague the family and crew and an unspeakable malevolence threatens to tear the very fabric of sanity from them all.