J. Michael Lennon’s biography is the first that interprets Mailer from within, not as a public spectacle. Unlike his predecessors—Mary V. Dearborn, Peter Manso, Carl Rollyson, and others—Lennon was Mailer’s friend and collaborator; he has read 45,000 of his letters, and talked to an enormous population of friends and enemies, from gangsters to editors. He shepherds a prodigious variety of events into well-organized chapters, sometimes cluttered with irrelevant details like the names and addresses of movie houses where Mailer watched gangster films as a teenager.