Fans of HBO’s “Game of Thrones” mini-series have been introduced to the character Jon Snow, but only readers deep into George R.R. Martin’s unfolding epic (five of seven projected volumes have been published) know of Ygritte and this line which she speaks repeatedly to the young, courageous but inexperienced hero. Honest civilians who read Joby Warrick’s new and incredibly riveting book “The Triple Agent: The al-Qaeda Mole Who Infiltrated the CIA” will acknowledge and accept a similar admonition about the limits of their own understanding of the war being waged every day from the wild border lands of Afghanistan and Pakistan across the many theaters into which global jihadism is metastasizing.

Warrick is the Washington Post’s national security correspondent, and readers can be forgiven if they mistake his new work of nonfiction for one of the recent best-selling spy thrillers from Alex Berenson, Vince Flynn, Daniel Silva or Brad Thor. “The Triple Agent” is all too real, however, and tragically so for it details the catastrophe that befell the CIA on Dec. 30, 2009, when an al Qaeda operative penetrated the agency’s inner sanctum in Khost, Afghanistan, and caused grievous carnage.