Marilynne Robinson’s new novel, “Jack,” is the fourth to be set among the world and people of a fictional town called Gilead, Iowa. The novelist grew up in Idaho, and, when she moved to the flatter country of Iowa, she “noticed that the landscape had a very high number of little colleges scattered over it,” she tells David Remnick, that were sometimes the oldest buildings in a town. “I wanted to know who had built these things, that this was how you would settle an empty landscape. And that was when I came across the abolitionist movement. Those were the people who did this.” From that history and culture, Robinson imagined Gilead and the old preacher named John Ames who narrates the first book in her series. “Jack” concerns the son of Ames’s closest friend, who was disgraced and left Gilead. The book finds Jack, who is white, in St. Louis and in a predicament: he is in love with a Black woman, at a time when an interracial relationship was a scandal and, in some places, a crime. Plus, the début novelist Douglas Stuart. After two decades of working in the fashion industry and dreaming about writing, Stuart recently published an acclaimed first novel, “Shuggie Bain.” He showed us around his old stomping grounds in New York’s garment district.