Hampton Sides discusses & signs his new book Hellhound on His Trail: The Stalking of Martin Luther King, Jr. and the International Hunt for His Assassin (Doubleday, $28.95). Sides' research on this subject forms much of the basis for PBS's documentary Road to Memphis, which originally aired on May 3. Sides illuminates not only the forces that culminated in King's assassination; he also reveals the largely forgotten story of how his death led to the largest manhunt in American history. His research included hundreds of thousands of unpublished documents including crime scene photos, police reports, unexpurgated FBI files, and audio tapes - all from a retired Memphis cop who has compiled the most comprehensive digital archive about the assassination. Sides says, "Every non-fiction writer needs to find a guy named Vince."