The Making Of Steve Bannon, by Barton Swaim.

Stephen K. Bannon, President Donald Trump’s chief strategist, grew up in a working-class suburb of Richmond, Va. He attended Benedictine College Preparatory, a Catholic military school, where he and his peers viewed rivals from wealthier prep schools with disdain. “We were the blue-collar guys,” recalls a school friend of Mr. Bannon in Joshua Green’s “Devil’s Bargain.” “They were the rich snobs. They’d always do the employer-employee joke at us: ‘When you grow up, you’ll work for us.’ And we’d punch ’em in the nose.” …

A reader of “Devil’s Bargain” who knew nothing about American politics and didn’t catch Mr. Green’s subtle but thoroughly unsympathetic judgments of his subject might come away thinking Mr. Bannon was the book’s hero: Everyone roots for an irreverent upstart who outrages a self-satisfied establishment and turns the system upside down. …

Mr. Bannon’s cultural conservatism — rooted, Mr. Green suggests, in the deeply traditionalist Catholicism in which he was raised — didn’t seem like a perfect fit for a libertine real-estate mogul and reality TV star. Mr. Trump, moreover, is notoriously averse to slovenly attire, and Mr. Bannon often gives the appearance of having just awakened from a night on a park bench.

Yet the two connected. Mr. Trump liked Mr. Bannon’s boldness, intelligence and contempt for ruling classes of all kinds. Mr. Bannon provided the aspiring president, Mr. Green contends, with two things he didn’t already have: first, “a fully formed, internally coherent worldview that accommodated Trump’s own feelings about trade and foreign threats, what Trump eventually dubbed ‘America first’ nationalism”; and, second, “an infrastructure of conservative organizations” — especially Breitbart News. …

For a year or more, Mr. Bannon has been portrayed in sharply unkind ways in the American news media—a bigot, a boor, a nutcase. But although Mr. Green is no admirer of Mr. Bannon’s politics, readers of “Devil’s Bargain” will not conclude that the subject is either unsophisticated or politically incompetent.

Whether in the end this unapologetic nationalist will get what he wants out of the title’s bargain—a durable populist revolution that subverts and weakens the cultural progressivism that dominates America’s media, education system and entertainment industry—remains as uncertain as ever.

The rebellion’s leader doesn’t share Mr. Bannon’s worldview in more than a superficial way and lacks his sustained commitment. But if I were a progressive, I wouldn’t get too complacent about it.