Last week, a former employee of the National Security Agency was indicted in connection with a leak of classified information about the NSA’s warrantless domestic surveillance program to a reporter.

As it progresses, the case will undoubtedly yield insightful information about a program shrouded in secrecy. But to delve into the background of how such a surveillance program came to be, a good place to start is Shane Harris’ new book, “The Watchers: The Rise of America’s Surveillance State.”

Harris is not the reporter leaked to by former NSA agent Thomas Drake. But Harris has been on the electronic surveillance, intelligence and counterterrorism beat for years at National Journal and covers similar terrain in the book.

“The Watchers” is a product of almost a decade of laborious interviews with government officials at the lowest and highest levels. Harris, who recently left National Journal for a post at Washingtonian magazine, investigates how technology has teamed with counterterrorism efforts in a digital age and “the conflict between security and liberty that lies at the heart of this war,” as he puts it.

“We have never lived in a time when the government has had such remarkable technological ability to watch its own citizens,” Harris writes.

Laid out more like a suspenseful thriller than a work of journalism, Harris leads us through the story with an unlikely protagonist: John Poindexter, a Navy admiral and national security adviser under President Ronald Reagan who was convicted of multiple felony counts in the Iran-Contra affair (the felonies were later overturned on appeal).

The story is largely that of Poindexter’s aspiration for Total Information Awareness, the namesake of an ambitious program that he spearheaded to monitor terrorism by making a massive interagency database of e-mails, phone calls and various records, and then drawing correlations between individuals and threats.

After 9/11, Poindexter resurfaced from his exile from government to found and head the Information Awareness Office, which aimed to meld several Defense Advanced Research Projects Agency projects to achieve the information awareness goal.

There, Poindexter was the Pentagon’s point man for creating a data-mining program that would connect the dots between disparate pieces of information to help agents seek out and prevent the implementation of terrorist plots like 9/11. Civil libertarians and privacy activists, however, decried the program when it came to light.

Because of its dubious nature, the fact that it largely lacked a way to prevent U.S. citizens’ information from being gathered unconstitutionally and Poindexter’s “tin ear for politics,” the program succumbed to media and Congressional scrutiny and was denied funding.

But the fundamental efforts didn’t stop, and the concept found a torchbearer in the NSA.

The agency to this day surreptitiously collects terabytes of information and plots them on a visual aid (sarcastically called the Big-Ass Graph, or BAG). Unfortunately, making sense of the dots and lines is no easy task. Forget finding a needle in a haystack, Harris says, it’s more like finding one needle in a pile of other needles.

“The NSA might be able to swallow the ocean. But what good was that if it could never digest it?” Harris asks. The NSA has “become very good at collecting dots but not at connecting them.”

In its thoroughness, Harris’ book suffers from a similar problem: In collecting so much information about his topic, Harris occasionally follows lengthy tangents that could have been shortened, like accounts of Congressional hearings or the military’s Able Danger program whose proponents claimed it could have turned up information about 9/11 hijacker Mohammed Atta — claims that have since been debunked.

But Harris makes accounts of high technology and wonky policy battles very readable and succeeds in delving into the psyche of Poindexter and the other surveillance proponents. These aren’t men who enjoy reading personal e-mails; they really believe in the mission of stopping terrorism at all costs.

Harris also poignantly critiques the NSA’s surveillance program, stating that it lacks oversight. Ostensibly the realm of Congress, the Foreign Intelligence Surveillance Court and the intelligence agencies themselves, the domestic surveillance programs go largely unpoliced.

The 2008 reauthorization by Congress of the Protect America Act institutionalized the program by authorizing warrantless surveillance, as long as the target is reasonably believed to be outside of the United States. But U.S. citizens are sometimes caught up in these massive information sweeps and nobody finds out until after the fact.

In the end, Harris calls for a reinvigorated debate about privacy standards. In the digital age, when a simple civilian Internet search can unearth mounds of information about citizens housed on social networking sites, does it still make sense to restrict the government from collecting this data?

“The meaning of privacy has changed and anonymity no longer exists,” Harris states. “The nation should come to terms with that fact.”

He urges us to have this debate now and not wait until another terrorist attack spurs fear and hyperbole and perhaps an impulsive erosion of more civil rights than we wish to cede. Perhaps with the Thomas Drake case on front pages and on people’s minds, Harris may get his wish.