Mae, a teenager with an inverted pentagram carved into her back, shows up in an Ohio hospital. Her case sparks the interest of hospital psychiatrist Dr. Suzanne Mathis, who offers to put the girl up in her home while looking for a suitable foster family. It's soon discovered that Mae escaped a devil-worshipping cult in the rural neighbouring county. Authorities have long tried to investigate the cult, but have been blocked by religious freedom issues and a fiercely protective county sheriff. It's not long before Mae's presence causes upheaval in the Mathis family.