"Harlot's Ghost", Mailer's longest novel (1310 pages), appeared in 1991 and received his best reviews since "The Executioner's Song". It is an exploration of the untold dramas of the CIA from the end of World War II to 1965. He performed a huge amount of research for the novel, which is still on CIA reading lists. He ended the novel with the words "To be continued" and planned to write a sequel, titled "Harlot's Grave", but other projects intervened and he never wrote it. "Harlot's Ghost" sold well.