Ari Aster now worryingly creates a losing streak with this bafflingly dull movie, a laborious and weirdly self-important satire which makes a heavy, flavourless meal of some uninteresting and unoriginal thoughts – on the Covid lockdown, online conspiracy theories, social polarisation, Black Lives Matter, liberal-white privilege and guns.

The movie looks good, courtesy of Darius Khondji’s cinematography, but has nothing new or dramatically vital to say, and moreover manages the extraordinary achievement of making Emma Stone, Pedro Pascal and Joaquin Phoenix look like boring actors. This is by virtue of its moderate script and by the unvarying stolid pace over its hefty running time which might have suited a 12-episode streamer.

Eddington is a fictional small town in New Mexico in the US, bordering Native American territory; we join the story as the Covid lockdown begins (though Trump is oddly unmentioned in all the news programmes and viral TikToks everyone’s watching) and Mayor Ted Garcia (Pedro Pascal) and Sheriff Joe Cross (Joaquin Phoenix) are at loggerheads – interestingly taking opposite sides to their counterparts in Spielberg’s Jaws on the personal liberty issue.

Here, the mayor insists on restrictive mask-wearing and Sheriff Cross refuses to wear his and is resentful of the mayor supporting construction plans for a giant new “online server farm” – gobbling up resources and symbolically sowing discord via the internet – and this complicates existing tensions.

Watch the trailer for Eddington.

The mayor once had emotional history with Cross’s wife Louise (Emma Stone) who now suffers from hysteria and depression and whose mother Dawn (Deirdre O’Connell), now uncomfortably “bubbled up” with them in the family home, is a querulous conspiracy theorist and social media addict – although the problem of how to make these particular things funny or interesting is one the film never solves.

Garcia’s insufferable teen son Eric (Matt Gomez Hidaka) is dating social justice warrior Sarah (Amélie Hoeferle) who is cartoonishly convulsed with guilt at her white privilege and at having dumped Michael (Micheal Ward) because he is now a cop, working for Sheriff Cross, and a gun enthusiast – though he is a person of colour.

The atmosphere of feverish resentment and wholesale offence-taking worsens with the George Floyd outrage and Louise and her mom take an interest in charismatic cult leader Vernon Jefferson Peak (Austin Butler) who has recovered memories of child abuse and encourages his followers to do the same.

So Sheriff Cross fights back against everything by running for mayor himself and winds up encouraging the townsfolk to get their guns ready for the coming showdown.

Mano-a-mano … Joaquin Phoenix and Pedro Pascal in Eddington. Photograph: Courtesy: Cannes Film Festival

This idea of a mano a mano political contest between these two grizzled alpha males promises some comedy – and the film does deliver one actual laugh with Mayor Garcia’s outrageously sugary TV ad, recounting his tough emotional courage raising his boy as a single dad.

And there is some divertingly acid, nasty satire on the odious attitudes on show in the sheriff’s department. One cop says sagely that blacks hate Hispanics because they are “fake minorities who are taking their coupons”. And when Native American cop Butterfly Jimenez (William Belleau) intervenes in an investigation, a white cop sneeringly asks if he shouldn’t be looking into an “alcoholic domestic dispute at one of your casinos”.

But it all feels secondhand – and a scene showing a fractious town meeting on zoom is weirdly like the legendary online council meeting in Handforth, Cheshire. There is no accumulation of drama or tension or intellectual revelation and the setpiece shootout is ultimately valueless. What exactly is it saying that we didn’t know already? The wait for Aster to recover his directorial form goes on.

Eddington premiered at the Cannes film festival. Global release dates are to be confirmed