Horror and suspense drama starring Jess (Michelle Monaghan), a recently separated woman who has to move to the old family farm with her teenage daughter, Tyler, and her eight-year-old son, Owen. One night the family dog detects something strange coming from the forest and goes looking for it. On her return from the forest darkness, she savagely attacks Owen. Jess urgently takes him to the hospital to treat the bites, but her condition worsens without anyone knowing the reason. Jess will discover a most disturbing cure.