In his cover story for The Atlantic magazine, the journalist Graeme Wood puts the Islamic State under the microscope. What is it? Where did it come from, and what does it want? Wood argues that ISIS seeks to revert civilization to a “seventh-century legal environment, and ultimately bring about the apocalypse,” and it’s committed to killing vast numbers of people in the process. Wood joins us Monday to explore ISIS’s intellectual genealogy and to explain why it’s imperative the West better understand it.