Mark Bowden has shaped a distinctive career among narrative journalists. While a star reporter for the Philadelphia Inquirer, he began writing narrative nonfiction books and magazine articles. He has most often explored a specialized turf -- organized teams waging a just war against evildoers.

His award-winning "Black Hawk Down" described the rescue of the survivors of a crash of a U.S. helicopter in Somalia during a firefight. It ran as a serial newspaper narrative and was later turned into a book and a film and an elaborately hypertexted Internet site.

Bowden's other books chronicle the reign and capture of a Colombian drug lord by U.S. Special Forces, the team systematically exposing a Philadelphia dentist with a second life as a major cocaine dealer, and the 444-day ordeal of the 51 U.S. Embassy captives in Tehran and their rescue by U.S. soldiers.

Along the way, Bowden published in 2003, in the Atlantic Monthly, a controversial defense of the judicious use of torture.

Now he combines his fascination with the potential of the Internet and his penchant for elite special teams of insiders in "Worm: The First Digital World War." He argues that the Internet has become integral to our nation's business and defense but is left mostly unguarded against destructive efforts by slick entrepreneurs and antagonistic governments. He offers up a well-researched case in point: the Conficker computer worm.

A few computer security experts, one inside Microsoft, noticed the worm late in 2008. Built by unknown parties with a Chinese hacking kit that was openly sold online, it was improved upon in untraceable and ingenious ways, then sent forth and stealthily installed itself in tens of millions of computers, poised to take over.

Bowden writes from deep behind the scenes, joining a posse of self-appointed, self-screened super-techies, inside and outside private companies, and far in advance of official U.S. agencies' efforts. His underlying aim is to show that "there is no such thing as an agency charged with protecting the Internet," and he doesn't much like that.

While his many pages of engineering explanations gave this reader only the briefest illusion of comprehending how the Web, and the worm, work, what remained clearest was his lionization of these crusaders. They are a barely characterized but much-admired, post-hacker posse of sophisticated techno-patriots, fighting evil in obscure high-tech ways usually seen only in space operas.

The good guys get appellations like, "brash 42-year-old San Francisco entrepreneur," "dour and irascible geek" and "burly transplanted South African." And together they are "white hats," "the best good guy-minds against the best bad-guy minds. Where else in life would you find such a clear-cut contest between good and evil?"

Bowden portrays a continuing struggle, unwinnable, eternal, worthy, and worth more and stealthier federal notice, waging the good fight against sinister dangers threatening our now-crucial Internet way of life. Bowden is a crusader here, portraying a universe populated with brilliant, self-sacrificing good guys, mistily menacing bad guys, and hapless, tree-hugging civilians barely aware of the continuous galactic struggle to protect them. And that idealized framework clouds readers' ability to discern just how much they should worry.

Mark Kramer, now retired, was founding director of the Nieman Program on Narrative Journalism at Harvard. He's recently helped start a continuing narrative nonfiction conference in Holland.