Peter Slevin talks about his biography of the first lady. Michelle Obama: A Life follows Mrs. Obama to the White House from her working-class childhood on Chicago’s largely segregated South Side, the daughter of of a city water-plant worker afflicted with multiple sclerosis. She faced tribulations at Princeton University and Harvard Law School during the racially charged 1980s, and returned to Chicago, where she works in an elite law firm and meets a law student from Hawaii named Barack Obama.