How can one write history so that it seems like a thriller? How does one write a biography without making the subject the centerpiece of the narrative? I have no idea if David Pietrusza asked himself these questions — or this one: How can history be written as a newspaper headline? Call this a biography by indirection. Franklin Delano Roosevelt is defined by competing individuals and movements: Huey Long, Father Coughlan, Al Smith, the Liberty League, Earl Browder and the Communist Party, Dr. Francis Townsend and the Townsend Plan, Norman Thomas and the Socialist Party. They threatened FDR’s majority in...