Sierra Six

Sierra Six is an action thriller novel by Mark Greaney, published on February 15, 2022 by Berkley Books. It is the eleventh book in the Gray Man series. The novel features two storylines, in which main character Court Gentry tracks down a Pakistani terrorist he had crossed paths with twelve years ago as a member of a CIA paramilitary operations unit. It debuted at number four on the New York Times bestseller list.