Allie wakes up, after taking her own life, in a room filled with memories in the form of photographs, negatives and slides that cover the floors and walls. Unable to move onto the other word, she slowly realizes that she can relive each memory. Allie comes to understand that the memories are picked by the room she now inhabits, forcing her to deal with problems she was originally running from.

Billie, a twenty something burnout, is tasked with house-sitting for her aunt and uncle, but after inviting some friends over, becomes convinced her teenage cousin Grace has stolen a notebook containing her latest screenplay. While hunting for the book in "Grace's Room", the gang uncovers a bloody trove of occult paraphernalia. Unbeknownst to Billie and her friends, said cult has been watching them from the nearby woods, and now must kill them for discovering too much. A gruesome assault on the house ensues as the gang struggles to survive the night.

As an epidemic of a lethal airborne virus - that kills within days - rapidly grows, the worldwide medical community races to find a cure and control the panic that spreads faster than the virus itself.