Stephen K. Bannon drinks Kombucha (who knew?), the fermented tea beverage for health fanatics that tastes like…well, if they ever invented a soft drink called Germs, that’s what Kombucha tastes like. In “The Brink,” Alison Klayman’s fly-on-the-wall, rise-and-fall-and-rise-of-a-white-nationalist documentary, Bannon explains that he likes Kombucha because it gives him a lift; he drinks it for the same reason he drinks Red Bull. At one point in the movie, he jokes that now that his Kombucha habit is going to be outed, the stock will probably drop by 50 percent. He means the stock for Kombucha, but for a moment you think he’s talking about the stock of Steve Bannon. How will it influence his image when the world learns that he craves the pause that refreshes the palettes of lefty progressives?

Bannon, as always, thinks he’s two steps ahead of us. (It’s part of his ’50s-salt-of-the-earth-meets-Goldman-Sachs-meets-The-Art-of-War élan.) “The Brink” is an impeccably crafted vérité ramble — an engaging and enraging, disturbing and highly revealing movie that follows the 64-year-old former chief strategist for Donald Trump over the last year and a half, starting the moment he was cut loose from the White House (he got fired on Aug. 18, 2017).

Bannon likes to come on as someone who doesn’t waste time worrying about his image (he’s got bigger fish to fry, like remaking the world). But his “anti-image” politics is, in fact, pure image. It’s there in his softball persona: the way he calls people “dude,” or wears two shirts at once, like flannel armor, or chuckles good-naturedly over the fact that during the 2016 presidential campaign people said he looked like a blotchy disheveled drunk. It’s there in the way he adopts an easygoing regular-guy folksiness that belies his self-styled reputation as a “firebreather,” or in the way he takes pictures with fans, posing a woman in between himself and another man so that he can grin and say, “A rose between two thorns.”

Steve Bannon, in a word, is courtly. He’s all warm smiles and friendly handshakes when he’s saying goodbye to the producer of a London TV news show on which an interviewer just tried to rip him a new one (“God, she’s tough,” he says with a twinkle, sucking down a Red Bull and sounding almost impressed). And when he pitches the leaders of far-right European political parties on the idea that “we help knit together this populist-national movement throughout the world,” he explains that he’s doing the same thing he did at Goldman Sachs, assembling deals that create possibilities, acting like that hip and viral thing, a connector, as he talks about organizing “conferences and stuff.”

Bannon has a way of revealing himself when he thinks he’s not, and “The Brink” opens with a startling scene in which he recalls touring the concentration camps at Auschwitz and Birkenau and realizing, to his surprise, that Birkenau was the haunting one; he learns that’s because Auschwitz used the already standing buildings of an old college, whereas Birkenau was constructed from scratch. He goes on, with perhaps a little too much admiration, about the wonders of German industrial design that went into the camp, but then he arrives at what’s supposed to be his PR money shot: the idea that the workers at prominent German companies — Mercedes Benz, etc. — who designed the nuts and bolts of the camps had no knowledge of the forces they were serving. He says, in essence, isn’t that amazing?

The intended subtext of his words is that we shouldn’t think of Bannon as an anti-Semite. He’s in full awe of the Holocaust, cognizant of that horrifying chapter of history. But Bannon, instead, winds up making an unconscious point about how darkness can wind up hiding from itself. And you can’t help but hear that point and think of Steve Bannon.

In “The Brink,” Bannon, after getting booted from the White House, still goes to bat for Donald Trump, capitalizing on his newly minted celebrity as the power behind Trump’s rise. But fate knocks him off his pedestal when he becomes the public face of the Roy Moore campaign in Alabama — and Moore, dogged by charged of pursuing underage girls, loses the election. It’s a bitter defeat for Bannon. And then, just a few weeks later, Michael Wolff’s “Fire and Fury” comes out, quoting Bannon as characterizing a Trump Tower meeting between Jared Kushner, Donald Trump Jr., and a Russian agent as “treasonous.” Suddenly, he’s persona non grata in far-right circles; he gets fired from Breitbart News and loses the financial backing of his benefactors, Robert and Rebekah Mercer. And it’s this chain of humiliations that leads him to go to a place that can still look up to him as a savior: Europe. For Bannon, it’s like a homecoming. He’s going back to the land of his white-supremacist roots.

Touring the power centers of Europe, Bannon is like a venture capitalist out to fund some new tech start-up, but what he’s funding, in a word, is hate. And he’s doing it by utilizing a time-honored advertising technique: He’s calling it something else. He’s taking racism and rebranding it. He meets with the former leaders of the French National Front party (now called National Rally), like Jérome Rivière, and Filip Dewinter, head of the Vlaams Belang Party of Belgium, and Kent Ekeroth, of the Swedish Democrats. They have a polite dinner party for cultivated Continental anti-immigrant populist nativists, and the fact that Bannon allowed this to be filmed at all speaks to his delusions of grandeur. A self-styled conquering hero, he’s focused on the European parliamentary elections of 2019, about which he says, “We’re gonna run the f—in’ tables on these guys.”

He’s trying to knit together a dozen separate national surges, trying to unify the “populist” strains of Europe into a right-wing supergroup that he calls…the Movement. He offers them things like polling data and “war-room analytics,” but what he’s really providing is the sense that, in his words, “It’s a global revolt. It’s a zeitgeist. We’re on the right side of history.” Talking to Paul Lewis, a journalist from London’s liberal-left newspaper The Guardian, he says, “I’m going to convert 20 percent of your guys.” So cocky is Bannon that when he gets out in front of an audience in Hungary, after all his disavowals of racism and anti-Semitism and his thin pretense that what he calls nationalism is merely an “economic” movement, he lets his freak flag fly. “We are working on building an old-school Christian democracy,” he says. Not much room for Muslims there (and maybe not much for Jews, either). This is no dog whistle — it’s Bannon putting out a clarion call.

“The Brink” is a far better and more penetrating film than Errol Morris’s Bannon portrait, “American Dharma,” which let Bannon bathe in his own aura. Klayman, the up-and-coming documentarian who has made superb films about Ai Weiwei (“Ai Weiwei: Never Sorry”) and psychotropic drugs (“Take Your Pills”), doesn’t get sucked in by the Bannon “charm.” She captures what a devious actor he is, and hangs around long enough to catch him in those rare moments when the mask comes off (like when the Republicans lose the House in the midterm elections, causing him to fly into a rage at some clueless pollster). The truth about Steve Bannon that “The Brink” nails is that he always sees “the future,” and it’s always about the revolutionary destiny of his cause, his people. Until he loses, at which point he reverts to looking like what he is: an armchair warrior who thinks any political movement built on something other than rage is for wimps.