Between October 2014 and November 2016, global terrorism expert Jessica Stern held a series of conversations in a prison cell in The Hague with Radovan KaradÚziÔc, a Bosnian Serb former politician who had been indicted for genocide and other war crimes during the Bosnian War and who became an inspiration for white nationalists. Though Stern was used to interviewing terrorists in the field in an effort to understand their hidden motives, the conversations she had with KaradÚziÔc would profoundly alter her understanding of the mechanics of fear, the motivations of violence, and the psychology of those who perpetrate mass atrocities at a state level and who--like the terrorists she had previously studied--target noncombatants, in violation of ethical norms and international law.