Pulitzer Prize-winning author and historian David E. Hoffman will be discussing his true-life espionage thriller “The Billion Dollar Spy: A True Story of Espionage and Betrayal” at the Main Library. Based on previously classified CIA documents and extensive interviews, Hoffman’s book details the complex motivation behind Adolf’s Tolkachev’s turning over of top-secret Soviet research and developments to the U.S. Hoffman who is a former Moscow correspondent for The Washington Post, now a contributing editor; the author of “The Dead Hand,” which details the last years of the United States-Soviet arms race; and a correspondent for PBS’s FRONTLINE. The event is free, but tickets are required.