Mario Puzo needed money. His first two novels, The Dark Arena (1955) and The Fortunate Pilgrim (1965), received good reviews but were not best sellers. He had an idea for his next novel, but his publisher wasn’t seeing dollar signs attached to it. “I was 45 years old and tired of being an artist,” Puzo wrote in The Godfather Papers and Other Obsessions. “I owed $20,000 to relatives, finance companies, banks and assorted bookmakers and shylocks. It was really time to grow up and sell out as Lenny Bruce once advised.” Puzo didn’t want to write about the Mafia, as his editors ...