Brain on Fire follows Cahalan (Moretz), a rising journalist at the New York Post who mysteriously starts having seizures and hearing voices. As weeks go by and Susannah rapidly descends into insanity, she moves inexplicably from violence to catatonia. Following a series of outbursts, misdiagnoses and a prolonged hospital stay, a lucky last-minute intervention by one doctor finally gives her a diagnosis and hope to rebuild her life.