A phrase that become a Twitter trend during the Trump Era pops to mind when watching “Within the Whirlwind” and recalling what the Russians under Stalin did to their own people to placate the paranoia of a megalomaniac.

“The cruelty’s the point.”

A story about the vast purges of “intellectuals” and anybody smart enough to recognize a diminutive despot in the making, the first of the millions sent to Soviet gulags in one flimsy “legal” pretext after another, this unjustly ignored Marleen Gorris (“Antonia’s Line”) gem contains perhaps the finest performance of Emily Watson‘s career.

Never heard of the movie or her performance in it (in 2009)? Talk about “snubbed.”

Watson (“The Theory of Everything,” “A Royal Night Out,” “Chernobyl”) plays Evgenia Ginzburg, a passionate teacher of Russian literature and poetry at Kazan University when we meet her, a lady with vast reservoirs of memory for the works of Pushkin and the other greats of the Russian canon.

A mother of two boys, married to the university newspaper editor (Benjamin Sadler), she is also a Communist Party member in good standing, and a true believer. Any bit of unsettling news husband Pavel passes on from Moscow gets a considered look, and an unworried response from Evgenia.

“I don’t know, but I’m sure they know what they’re doing.”

Pavel is weighing facts and seeing signs as he tosses her latest “story” on the Party’s sanctioned food and manufacturing production figures in the bin.

Sure enough, they see a respected colleague (Pierce Quigley) abruptly arrested in front of them, hauled away for his possible association with Stalin’s biggest boogeyman, the Red intellectual Leon Trotsky. Everybody had best distance themselves from their “Trotskyite” friend, and quick.

When Pavel lets his wife know he’s apologized to local Party bosses for her “association,” Evgenia is livid. Soviet rewriting of history, something we’re seeing in America as I type this, is in full swing. Evgenia’s “crime” is that she didn’t “suspect” Yevlov, the colleague, that she didn’t rat out this Party endorsed friend before anybody knew Stalin’s goons were going to accuse him.

The idealistic Evgenia won’t repeat this act of contrition in front of the myopic, officious apparatchik who has a confession for her to sign. She figures she has rights. She has people she can appeal to.

She lacked “political vigilance” about the already rewritten history of this Yevlov’s rise? She’ll show them.

But damned if the smirking goon from the capital Beylin (Ian Hart) doesn’t take an instant disliking to this “arrogant” and smart member of the “elite.” Appeals and assurances from others disappear as she’s put on trial, where she outlawyers the ignorant mugs assigned to judge her. “Tell me, who am I suppose to have ‘terrorized?'”

That, or course, seals her fate. Ten years in a camp it is. That’ll teach her to be smarter, to have ideals, to insult deplorable men with authority.

Evgenia finds herself torn from her family, renounced by her save-my-own-skin husband, denounced by comrades she tried to help and stuffed in a cattle car with scores of other freezing, starving women on her way to Siberia.

Much of Gorris’s film is standard Gulag/concentration camp horror — the brutal labor conditions of a lumber camp, the subfreezing weather, the “400 grams of bread a day” diet, the rape culture of the callous, hair-trigger guards.

Evgenia lives, cut off from home, desperate for any word of Kazan from strangers from other camps she stumbles into. She keeps her own and others’ spirits up by telling stories from literature and reciting poems from memory in the barracks. She loses the last shred of “The investigators made a mistake” idealism that many shared when they first boarded that train.

As women walk off into the woods to die, or starve and give up, the cynicism of the history-altering state settles in among them all. How did you end up here?

“That was a long time ago,” is their mantra. “And it never happened, anyway.”

Watson doesn’t oversell the “pluck” of Ginzburg, whose memoir this is based on. She portrays the woman as smart, logical and naive, someone who figures reason, truth and the law will protect her.

She shows us the exterior ordeal and interior suffering of a woman who figures she has to survive this sentence (as if the Party is bound to keep its promise about the length of political prison sentences) for her children. She has to try and protect her sanity and her dignity, resisting the sex-for-food come-ons of the monsters who guard them.

Watson lets us see the layer of callouses and scabs that crust over this woman’s once hopeful heart. It’s a magnificent performance.

Hart makes a perfectly vile impression as the kommissar who makes it his business to put this Jewish academic in her place. And Ulrich Tukur shines as a (pre-war) doctor of German descent, imprisoned because of his lineage, but necessary to the camp and thus tolerated as he treats his patients with compassion and firmly defends them from being worked and starved to death.

“Within the Whirlwind” doesn’t break much new ground in historical terms or its depiction of the Reign of Terror that the purges were, or in its assessment of how quickly people succumb to inhumanity — in how they treat others, in how they think of themselves.

But it’s a hidden gem, one of Gorris’s best and a high water mark for an actress nominated for Oscars for “Hilary and Jackie” and “Breaking the Waves,” and an Emmy nominee for “Chernobyl.”

Rating: unrated, violence, including rape

Cast: Emily Watson, Agata Buzek, Ulrrich Tukur, Pierce Quigley and Ian Hart.

Credits:Directed by Marleen Gorris, scripted by Nancy Larson, based on the memoir by Eugenia Ginzburg. A Corinth Films release.

Running time: 1:40