"Sharp, cinematic, and packed with action the Gray Man novels blow all other thrillers away!" Brad Thor,#1New York Times bestselling author of Black Ice
"So many bad guys, so little time....Over-the-top thrills. Greaney never disappoints." Kirkus Reviews
"Excellent....Greaney seamlessly adjusts focus between the timelines, jumping from one exhilarating roller-coaster ride to the other. Spy and military thriller fans will be well pleased." Publishers Weekly (starred review)
Greaney hit absolute literary gold with his Gray Man series and Sierra Six is no exception! Mystery & Suspense magazine
In his research for the Gray Man novels, Mark Greaney has traveled to more than thirty-five countries and trained alongside military and law enforcement in the use of firearms, battlefield medicine, and close-range combative tactics. He is also the author of the New York Times bestsellers Tom Clancy Support and Defend, Tom Clancy Full Force and Effect, Tom Clancy Commander in Chief, and Tom Clancy True Faith and Allegiance. With Tom Clancy, he coauthored Locked On, Threat Vector, and Command Authority.