Susannah Cahalan woke up one day in an unfamiliar hospital room, unable to move or speak, with no recollection of the psychosis and violent behavior caused by a rare autoimmune disease in which her body was attacking her brain. The fast-moving illness, thought to be the cause of “demonic possession” throughout history, overwhelmed Cahalan in just a few short weeks, and the result could have been a lifetime of institutionalization or possibly even death. The newly diagnosed ailment and the last-minute intervention that saved her are the subjects of her memoir, Brain on Fire, as well as this talk between Cahalan—now a writer for the New York Post—and neuroscience graduate student Carl Schoonover.