Alison Klayman, the granddaughter of Holocaust survivors, begins The Brink, her fly-on-the-wall documentary about ultra-nationalist Steve Bannon, with his thoughts on the Nazis.

“My sh*t at Auschwitz rocked,” Bannon, former confidant and aide to Donald Trump, tells the camera, describing one of his “craziest” propaganda films he shot there. When he said this, Klayman had been filming him for nearly a year.

She travelled with him over 13 months in 2017 and 2018 as he went from rally to meeting to rally, trying to cement Trump-style populism in America and export it to Europe.

What he said next about the Holocaust, Klayman thinks, was Bannon trying be both his usual “provocative” self but also saying something he thought she might approve of.

In the same tone of awe and bemusement with which he described his “sh*t at Auschwitz” moments earlier, Bannon claims to have been underwhelmed by the camp, a pre-war building the Nazis merely took over.

Birkenau, the purpose-built death camp, is where he was shocked, calling it the “pinnacle of German industrial design”, built by people who he says “were not devils”, working in offices far removed from what was happening.

Klayman tells the JC she knew almost straightaway this was how she would open her film.

“I was thinking: ‘How do I connect what they’re doing to the consequences,’” she says.

“He was, without knowing, talking about himself and the questions I wanted to explore.”

Klayman is quiet behind the camera for nearly all of her film.

She follows Bannon as he travels the world by private jet — a combination of media entrepreneur, rabble rouser at rallies and unceasing shmoozer with fans who want selfies, journalists who want interviews and far-right politicians who want support.

In one meeting with European Nationalists, Bannon listens to a Belgian politician say “the key problem is integration, Islam, so-called refugees”.

Legendary documentary maker Errol Morris — whose own Bannon film got mixed reviews — has said the man gives people “permission to hate”.

Klayman’s film is not so direct. It documents Bannon in private: his rages at his staff, his shady sources of funding and his coming unstuck when confronted for working with those he privately admits are neo-Fascists.

The documentary ends with a simple dedication to “Irving and Helen Kornbrot, z’L”.

Klayman’s Polish-born grandparents were big early influences on her. She speaks proudly of how, after both losing so many family members, they remained observant as they toiled in New York’s garment district as tailors.

She was close to them but they died before she felt “brave enough” to ask in detail what they happened to them in the Shoah.

She, her brother and her cousins all went to Jewish day schools in Philadelphia and she says Holocaust memory is “ingrained in my family… the cornerstone of my Jewish identity”.

Her Hebrew name is Tovah, after one of her grandfather’s sisters who was murdered.

When asked how her background influenced her politics, she says she fears where “baseless hatred” can lead.

She became involved with the project when the producer Marie Therese Guirgis, who worked for Bannon in the early 2000s when he was trying to become a Hollywood power-broker, convinced him to let a filmmaker shadow him.

Klayman was fearful she could waste months trying to expose him. She saw how he approached interactions with journalists “like combat” and tried to dominate the narrative with his own radio shows and films.

“My tactic was just to hope he was underestimating me and never underestimate him.”

She filmed nearly all the time she was with him.

He would introduce her as a “Commie lefty film-maker”and have long conversations as she asked questions, while giving away very little about herself, let alone being the Jewish descendant of Holocaust survivors.

She films Bannon negotiating with a Chinese billionaire for a huge cash injection.

She films his post-interview dust-up with a Guardian journalist who tells Bannon that “globalist” is “dog-whistle antisemitism”, then attacks Bannon’s “jokey, smirky” claim it is not.

One of the few moments Klayman’s voice can be heard in the film is after the Pittsburgh synagogue shooting. A man has killed 11 Jews as they worshipped, convinced their shul’s involvement in a charity that helps Muslim refugees was a conspiracy to replace white people.

Filming Bannon in the back of an SUV scrolling on his phone, she says “globalist” really is antisemitic, prompting another blithe dismissal from him.

“I really was angry. Of course he never concedes as a point of strategy. That’s why I put that in the film.”

Shortly after their exchange, Bannon jokingly introduced Klayman as a globalist, she reveals.

When asked if Bannon’s rhetoric contributed to the Pittsburgh shooting, she says: “When you’re doing political messaging and propaganda for a living, you chose your words very carefully…

“He’s a grown man. He doesn’t get to shirk that responsibility.”

Klayman thinks she succeeded by what her film doesn’t reveal as well as what it does.

In private, no one in Bannon’s movement is offering a vision for a better world.

She calls them “a lot of self-interested, not very bright people” whom the film shows on a “very human level”.

She adds: “Nazis were just people, too. There was a lot of underestimating, laughing at them…“If you expect evil is going to come looking like a monster, you’re probably going to miss some signs along the way.”

So does she think that Bannon himself is evil? “What he is willing to do,” she says, “the hatred, the disinformation, I think is quite evil. His tactics and what he wants to achieve are by my definition evil.”

Klayman is heartened that Bannon has not been able to use the film for self-promotion since its American premiere earlier this year. Tellingly, the man who is rarely off someone’s airwaves has never spoken publicly about it.

He showed no emotion when the producer screened it for him. He later cut off all contact with her.

“She said to me, ‘You know if he thought this movie was good for him, he’d be buying me a steak dinner’,” says Klayman.

“He’s not pleased with the film but fundamentally he’s the least important audience member.”

‘The Brink’ is in cinemas and on demand now