Mr. Risen also delves into the human wreckage left behind by the war on terror, portraying the hellish post-Army life of Damien M. Corsetti, a soldier who, by Mr. Risen’s account, engaged in torture at the Abu Ghraib prison west of Baghdad. He illustrates what the United States Army should have known before going into Iraq, that torture has two victims: the one who suffers it and the one who inflicts it. Mr. Corsetti is shown living in Savannah, Ga., having kicked an addiction to heroin, but living in a cloud of marijuana smoke with post-traumatic stress disorder. “He is one of the first veterans known to have been given full disability based on PTSD suffered while conducting harsh interrogations in the war on terror,” Mr. Risen writes.

The best section of the book is probably the last, about the trespasses against the United States Constitution committed by the National Security Agency. Here, Mr. Risen’s style becomes clearer and his narrative surer. The tale of Diane Roark, who worked on the staff of the House Intelligence Committee, is both hair-raising and representative of the post-Sept. 11 era, in which accountability and transparency in government, basic elements of a functioning democracy, were badly eroded. When she realized that the N.S.A. was collecting data on American citizens, she tried to find out more, and then to warn people. She assumed that she had stumbled across a rogue operation. She asked members of Congress about it, and got nowhere. She then contacted a federal judge who oversaw intelligence matters, only to have the judge report her to the Justice Department. She went to officials she knew at the C.I.A. and the White House.

Ms. Roark eventually realized that all these people had known about the N.S.A. program, and effectively approved of it. She retired from her Congressional job and moved to Oregon, only to wake up one morning in July 2007 to find F.B.I. agents with a search warrant and a sealed affidavit that allowed them to go through her house, apparently to look for evidence that she leaked data about the N.S.A. to newspaper reporters. Mr. Risen notes that others who discussed their concerns about the N.S.A.’s constitutional transgressions received similarly harsh handling, one reason that Edward J. Snowden fled overseas when he leaked documents about United States intelligence agencies’ surveillance of American citizens.

To follow Mr. Risen on this journey, the reader must hack through some undergrowth. For example, is it really necessary to write twice that “crazy became the new normal in the war on terror”?

Mr. Risen also sometimes overreaches. He states flatly that, “Every general in the military hoped to cash out by going to work for a major defense contractor as soon as he or she retired from active duty.” This is true of too many retired generals and admirals, but hardly all. Large numbers go into nonprofit work or academia. For example, off the top of my head, I know of a Marine general who joined a drug addiction rehabilitation charity and an Army lieutenant general who just finished a doctoral dissertation at Johns Hopkins University on “just war” theory in ancient Greek philosophy.