“Data rights are human rights.” That’s the rallying cry that emerges from The Great Hack, Karim Amer and Jehane Noujaim’s startling feature-length Netflix documentary, available on the streaming service from today.

You’d do well to make it your mantra. You should try chanting it the next time you log into your Facebook account. Better still, do it whenever you finally get around to deactivating or deleting it forever.

The film, which runs a hefty two hours and is dense in detail, much of it disturbing and some downright scary, should chill to the marrow anyone who cares about democracy and its future, which is looking more uncertain by the week.

Ostensibly, it’s about the Cambridge Analytica scandal: the harvesting by the British data research company of millions of personal details from Facebook users, who gleefully responded to an innocuous-looking “personality questionnaire”, in the process handing over their likes, dislikes, fears and, crucially, prejudices.

But it’s also about the illusion of freedom of choice, the manipulation of voters and the fragility of democracy, and how easy it can be polluted, corrupted.

Cambridge Analytica has tampered in a lot of elections worldwide — a staggering number, briskly ticked off here in a gobsmacking montage.

But its two biggest clients were the 2016 Trump election campaign and the Leave.EU campaign, headed by Arron Banks, the chief Bad Boy of Brexit, who tried to prevent the documentary being shown.

This vast treasure trove of data was massaged into content — propaganda, woven together from lies and misinformation — targeted at the “persuadables”, those who hadn’t completely made up their minds and could be easily swayed in one direction or the other. Trump or Hillary? Leave or remain? All it took was a nudge.

“We’re talking about building a personality profile of every voter,” says Christopher Wylie, the former Cambridge Analytica employee-turned-whistleblower. “You’re playing with the psychology of an entire nation.”

One of the most jaw-dropping statistics, among many, the film throws up is that the Trump campaign spent a million dollars a week on Facebook adverts, while the Clinton campaign spent only a fraction of that. This was the nudge.

The Great Hack features a rogues’ gallery of liars and chancers: Trump, Farage, Bannon, former Cambridge Analytica CEO Alexander Nix, who’s shown blatantly lying that the company has no involvement with the Trump or Brexit brigade, juxtaposed with documentary evidence, not least the undercover Channel 4 investigation, of him boasting about how he and his cohorts won it for both of them.

And let’s not forget Facebook supremo Mark Zuckerberg, whose social media platform was and still is the toxic enabler of all the meddling and manipulating. That’s the bigger story.

There’s a hero, too: The Guardian and Observer reporter Carole Cadwalladr, whose fearless, tireless reporting, in the face of legal threats and coordinated online abuse, blew the lid off the story.

But the documentary unfolds mostly through two parallel journeys: that of American academic David Carroll, who used the UK legal system to force Cambridge Analytica to release the data it holds on him (he ultimately failed when the company folded up its tent), and of former company higher-up Brittany Kaiser, a key figure at the core of all the dirty deeds who’s become a bit of a whistleblower herself.

Repentance or self-preservation? Hard to say — she’s so evasive, her shadow might have trouble trusting her — and harder still to care. She’s not the victim here, even though she acts the part.

It’s a gripping, must-see film, yet ultimately a depressing one, because you know that this is still going on every day, invisibly. Only the company names have changed.

The Great Hack is now streaming on Netflix.

Herald