Mark Greaney is the bestselling author of four Gray Man titles, and also co-author of three books with Tom Clancy. A feature film adaptation of The Gray Man is in development by New Regency Pictures. Mark has a degree in International Relations and Political Science. To research his novels, Mark has travelled all over the world and trained with firearms, visited the Pentagon and multiple Washington, D.C. Intelligence agencies, and studied close quarters battle tactics and battlefield medicine. He lives in Memphis, Tennessee.