There’s a grand tradition in disaster movies, one revived by “crazy” “conspiracy nut” Björn in the Swedish thriller “The Unthinkable.”

At some point, this would-be Jeremiah, who years before ran off his family with his mania, looks out over a Sweden descending into chaos, under assault by the boogeyman he always saw, and utters the words every “crank” throughout history longs to say.

“Why am I always right?”

“The Unthinkable” is a nervy paranoid thriller structured like a disaster movie. We see Björn (Jesper Barkselius) try to share his obsession with his musically-inclined teen son son, flying his small plane over tankers smuggling Russian crude through the Baltic, snapping photos. And we see the damage caused by his mercurial moods, a man never taken seriously by officialdom raging at his family, pushing them away in the process.

Years later young Alex (Christoffer Nordenrot) has become a famous experimental musician, long-estranged from his father. He’s chilly, closed-off emotionally. But a chance encounter with that first love who moved away, Anna (Lisa Henni) could change that.

It’s too bad this happens just as Sweden experiences huge terrorist attacks — on transport, then communications and you-can-guess-what-comes-next, because, dammitall, Björn did.

His long-ago military service taught him what millions of MAGAs and NRA nuts in America forgot. When bad things happen in the world, it’s usually something the Russians did. Tension over a canceled pipeline suggests that maybe “IS” or “jihadists” aren’t behind this violence.

Always neutral, always above-it-all Sweden is under assault, Crimea-style. Secret commandos, black helicopters and hell’s bell’s, the whole country has forgotten how to drive their Volvos in safety.

Is there something in air, the drinking water, the rain?

Alex, Anna and Anna’s bureaucrat mother (Pia Halvorsen) wait for answers and seek shelter in bunkers. Government has been decapitated. Cell phones are silent. The military is unprepared for this asymmetric warfare.

But Björn? His rising suspicions and actual evidence that, as even Alex has noted, “something’s up” (in Swedish with English subtitles) hasn’t made him any more convincing to eye-rolling colleagues and the authorities. He finds himself in his underground hydropower station, facing commandoes with his own brand of asymmetric warfare.

Director and co-writer Victor Danell has taken to billing himself as “Crazy Pictures,” because why should pop stars have all the fun? He’s made a thriller calculated to keep us as in the dark as everybody but Björn, puzzling over the chaos breaking out all over their orderly society. He succeeds, more often than not.

The domestic tragedy prologue and Alex/Anna melodrama that tracks through the film personalize the story, but add little as they slow it down.

Alex as a character is on-the-spectrum problematic. Working with him or carrying a torch for him seems…ALMOST unthinkable.

It’s the depictions of social breakdown, Swedish tempers exploding, soldiers questioning their priorities in an absence of orders and the action beats — Björn’s crackpot defense of the power station — that drive the narrative, punching through one Big Effect, crash or firefight right into the next.

American viewers may be grateful to catch this picture now, and not in 2018 when it was finished. Tiny Sweden forced to stand alone against Russian aggression seems a little less likely since Jan. 20.

Sure, the paranoia that makes “The Unthinkable” plausible would have worked better back then. But who’d have had time to stress over a movie about what Russian puppets would allow, when there was so much else to worry about at the time?

MPA Rating: unrated, violence

Cast: Christoffer Nordenrot, Lisa Henni, Jesper Barkselius, Pia Halvorsen

Credits: Directed by Victor Danell, aka “Crazy Pictures,” scripted by Victor Danell and Christoffer Nordenrot A Magnet release (May 7).

Running time: 2:09