In a crowded Democratic field, the candidate Julián Castro is eager to stand out. One way he’s tried to do that is by taking on the issue of immigration—a favorite topic of President Donald Trump, and one that’s important to his base. In a wide-ranging conversation with the New Yorker editor David Remnick, Castro lays out his plan. And Taylor Mac, a performance artist and playwright who made a name for himself in New York City’s downtown theater scene, makes the leap to Broadway.