MARK GREANEYMark Greaney is the co-author of three Number One Sunday Times bestsellers with Tom Clancy: Locked On, Threat Vector and Command Authority. In his research for these novels, Greaney travelled to seven countries and trained alongside military and law enforcement in the use of firearms, battlefield medicine and close-range combat tactics. He now writes for the Tom Clancy series of novels alongside Grant Blackwood. He lives in Memphis, Tennessee. Read More Read Less