One of the hot trends in the food world is one of the oldest: fermentation. No longer just for beer and sauerkraut, fermentation—which Helen Rosner calls “bacteria engaging with your food”—is the subject of cookbooks, and the specialty of destination restaurants like Noma, in Copenhagen, which has been called the world’s best restaurant for several years. René Redzepi, the chef at Noma, and David Zilber, the director of its fermentation lab, visited Rosner’s home kitchen to give her a lesson. A couple of weeks later, after the microbes had done their work, she brought some highly unusual fermented snacks to share with David Remnick. Plus, Dexter Filkins traces the rise to power of the Saudi crown prince, Mohammed bin Salman. Long before the international furor over the murder of the journalist Jamal Khashoggi—back when bin Salman was still being hailed as a reformer—Filkins says that he eliminated political opponents, cracked down on the press, extorted other wealthy royals, and arrested human-rights activists.