When Norman Mailer began his novel Barbary Shore, there was no plan to have a Russian spy as a character. As he worked on it, he introduced a Russian spy in the U.S. as a minor character. As the work progressed, the spy became the dominant character in the novel. After the novel was completed, the U.S. Immigration Service arrested a man who lived just one floor above Mailer in the same apartment building. He was Colonel Rudolf Abel, alleged to be the top Russian spy working in the U.S. at that time.